build: move package sources from src/pkg to src

Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.

10 files changed, 5751 insertions, 0 deletions

diff --git a/src/database/sql/convert.go b/src/database/sql/convert.go
new file mode 100644
index 000000000..c0b38a249
--- /dev/null
+++ b/src/database/sql/convert.go
@@ -0,0 +1,299 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Type conversions for Scan.
+
+package sql
+
+import (
+	"database/sql/driver"
+	"errors"
+	"fmt"
+	"reflect"
+	"strconv"
+)
+
+var errNilPtr = errors.New("destination pointer is nil") // embedded in descriptive error
+
+// driverArgs converts arguments from callers of Stmt.Exec and
+// Stmt.Query into driver Values.
+//
+// The statement ds may be nil, if no statement is available.
+func driverArgs(ds *driverStmt, args []interface{}) ([]driver.Value, error) {
+	dargs := make([]driver.Value, len(args))
+	var si driver.Stmt
+	if ds != nil {
+		si = ds.si
+	}
+	cc, ok := si.(driver.ColumnConverter)
+
+	// Normal path, for a driver.Stmt that is not a ColumnConverter.
+	if !ok {
+		for n, arg := range args {
+			var err error
+			dargs[n], err = driver.DefaultParameterConverter.ConvertValue(arg)
+			if err != nil {
+				return nil, fmt.Errorf("sql: converting Exec argument #%d's type: %v", n, err)
+			}
+		}
+		return dargs, nil
+	}
+
+	// Let the Stmt convert its own arguments.
+	for n, arg := range args {
+		// First, see if the value itself knows how to convert
+		// itself to a driver type.  For example, a NullString
+		// struct changing into a string or nil.
+		if svi, ok := arg.(driver.Valuer); ok {
+			sv, err := svi.Value()
+			if err != nil {
+				return nil, fmt.Errorf("sql: argument index %d from Value: %v", n, err)
+			}
+			if !driver.IsValue(sv) {
+				return nil, fmt.Errorf("sql: argument index %d: non-subset type %T returned from Value", n, sv)
+			}
+			arg = sv
+		}
+
+		// Second, ask the column to sanity check itself. For
+		// example, drivers might use this to make sure that
+		// an int64 values being inserted into a 16-bit
+		// integer field is in range (before getting
+		// truncated), or that a nil can't go into a NOT NULL
+		// column before going across the network to get the
+		// same error.
+		var err error
+		ds.Lock()
+		dargs[n], err = cc.ColumnConverter(n).ConvertValue(arg)
+		ds.Unlock()
+		if err != nil {
+			return nil, fmt.Errorf("sql: converting argument #%d's type: %v", n, err)
+		}
+		if !driver.IsValue(dargs[n]) {
+			return nil, fmt.Errorf("sql: driver ColumnConverter error converted %T to unsupported type %T",
+				arg, dargs[n])
+		}
+	}
+
+	return dargs, nil
+}
+
+// convertAssign copies to dest the value in src, converting it if possible.
+// An error is returned if the copy would result in loss of information.
+// dest should be a pointer type.
+func convertAssign(dest, src interface{}) error {
+	// Common cases, without reflect.
+	switch s := src.(type) {
+	case string:
+		switch d := dest.(type) {
+		case *string:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = s
+			return nil
+		case *[]byte:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = []byte(s)
+			return nil
+		}
+	case []byte:
+		switch d := dest.(type) {
+		case *string:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = string(s)
+			return nil
+		case *interface{}:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = cloneBytes(s)
+			return nil
+		case *[]byte:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = cloneBytes(s)
+			return nil
+		case *RawBytes:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = s
+			return nil
+		}
+	case nil:
+		switch d := dest.(type) {
+		case *interface{}:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = nil
+			return nil
+		case *[]byte:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = nil
+			return nil
+		case *RawBytes:
+			if d == nil {
+				return errNilPtr
+			}
+			*d = nil
+			return nil
+		}
+	}
+
+	var sv reflect.Value
+
+	switch d := dest.(type) {
+	case *string:
+		sv = reflect.ValueOf(src)
+		switch sv.Kind() {
+		case reflect.Bool,
+			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
+			reflect.Float32, reflect.Float64:
+			*d = asString(src)
+			return nil
+		}
+	case *[]byte:
+		sv = reflect.ValueOf(src)
+		if b, ok := asBytes(nil, sv); ok {
+			*d = b
+			return nil
+		}
+	case *RawBytes:
+		sv = reflect.ValueOf(src)
+		if b, ok := asBytes([]byte(*d)[:0], sv); ok {
+			*d = RawBytes(b)
+			return nil
+		}
+	case *bool:
+		bv, err := driver.Bool.ConvertValue(src)
+		if err == nil {
+			*d = bv.(bool)
+		}
+		return err
+	case *interface{}:
+		*d = src
+		return nil
+	}
+
+	if scanner, ok := dest.(Scanner); ok {
+		return scanner.Scan(src)
+	}
+
+	dpv := reflect.ValueOf(dest)
+	if dpv.Kind() != reflect.Ptr {
+		return errors.New("destination not a pointer")
+	}
+	if dpv.IsNil() {
+		return errNilPtr
+	}
+
+	if !sv.IsValid() {
+		sv = reflect.ValueOf(src)
+	}
+
+	dv := reflect.Indirect(dpv)
+	if dv.Kind() == sv.Kind() {
+		dv.Set(sv)
+		return nil
+	}
+
+	switch dv.Kind() {
+	case reflect.Ptr:
+		if src == nil {
+			dv.Set(reflect.Zero(dv.Type()))
+			return nil
+		} else {
+			dv.Set(reflect.New(dv.Type().Elem()))
+			return convertAssign(dv.Interface(), src)
+		}
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		s := asString(src)
+		i64, err := strconv.ParseInt(s, 10, dv.Type().Bits())
+		if err != nil {
+			return fmt.Errorf("converting string %q to a %s: %v", s, dv.Kind(), err)
+		}
+		dv.SetInt(i64)
+		return nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		s := asString(src)
+		u64, err := strconv.ParseUint(s, 10, dv.Type().Bits())
+		if err != nil {
+			return fmt.Errorf("converting string %q to a %s: %v", s, dv.Kind(), err)
+		}
+		dv.SetUint(u64)
+		return nil
+	case reflect.Float32, reflect.Float64:
+		s := asString(src)
+		f64, err := strconv.ParseFloat(s, dv.Type().Bits())
+		if err != nil {
+			return fmt.Errorf("converting string %q to a %s: %v", s, dv.Kind(), err)
+		}
+		dv.SetFloat(f64)
+		return nil
+	}
+
+	return fmt.Errorf("unsupported driver -> Scan pair: %T -> %T", src, dest)
+}
+
+func cloneBytes(b []byte) []byte {
+	if b == nil {
+		return nil
+	} else {
+		c := make([]byte, len(b))
+		copy(c, b)
+		return c
+	}
+}
+
+func asString(src interface{}) string {
+	switch v := src.(type) {
+	case string:
+		return v
+	case []byte:
+		return string(v)
+	}
+	rv := reflect.ValueOf(src)
+	switch rv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return strconv.FormatInt(rv.Int(), 10)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return strconv.FormatUint(rv.Uint(), 10)
+	case reflect.Float64:
+		return strconv.FormatFloat(rv.Float(), 'g', -1, 64)
+	case reflect.Float32:
+		return strconv.FormatFloat(rv.Float(), 'g', -1, 32)
+	case reflect.Bool:
+		return strconv.FormatBool(rv.Bool())
+	}
+	return fmt.Sprintf("%v", src)
+}
+
+func asBytes(buf []byte, rv reflect.Value) (b []byte, ok bool) {
+	switch rv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return strconv.AppendInt(buf, rv.Int(), 10), true
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return strconv.AppendUint(buf, rv.Uint(), 10), true
+	case reflect.Float32:
+		return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 32), true
+	case reflect.Float64:
+		return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 64), true
+	case reflect.Bool:
+		return strconv.AppendBool(buf, rv.Bool()), true
+	case reflect.String:
+		s := rv.String()
+		return append(buf, s...), true
+	}
+	return
+}
diff --git a/src/database/sql/convert_test.go b/src/database/sql/convert_test.go
new file mode 100644
index 000000000..98af9fb64
--- /dev/null
+++ b/src/database/sql/convert_test.go
@@ -0,0 +1,348 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sql
+
+import (
+	"database/sql/driver"
+	"fmt"
+	"reflect"
+	"runtime"
+	"testing"
+	"time"
+)
+
+var someTime = time.Unix(123, 0)
+var answer int64 = 42
+
+type conversionTest struct {
+	s, d interface{} // source and destination
+
+	// following are used if they're non-zero
+	wantint   int64
+	wantuint  uint64
+	wantstr   string
+	wantbytes []byte
+	wantraw   RawBytes
+	wantf32   float32
+	wantf64   float64
+	wanttime  time.Time
+	wantbool  bool // used if d is of type *bool
+	wanterr   string
+	wantiface interface{}
+	wantptr   *int64 // if non-nil, *d's pointed value must be equal to *wantptr
+	wantnil   bool   // if true, *d must be *int64(nil)
+}
+
+// Target variables for scanning into.
+var (
+	scanstr    string
+	scanbytes  []byte
+	scanraw    RawBytes
+	scanint    int
+	scanint8   int8
+	scanint16  int16
+	scanint32  int32
+	scanuint8  uint8
+	scanuint16 uint16
+	scanbool   bool
+	scanf32    float32
+	scanf64    float64
+	scantime   time.Time
+	scanptr    *int64
+	scaniface  interface{}
+)
+
+var conversionTests = []conversionTest{
+	// Exact conversions (destination pointer type matches source type)
+	{s: "foo", d: &scanstr, wantstr: "foo"},
+	{s: 123, d: &scanint, wantint: 123},
+	{s: someTime, d: &scantime, wanttime: someTime},
+
+	// To strings
+	{s: "string", d: &scanstr, wantstr: "string"},
+	{s: []byte("byteslice"), d: &scanstr, wantstr: "byteslice"},
+	{s: 123, d: &scanstr, wantstr: "123"},
+	{s: int8(123), d: &scanstr, wantstr: "123"},
+	{s: int64(123), d: &scanstr, wantstr: "123"},
+	{s: uint8(123), d: &scanstr, wantstr: "123"},
+	{s: uint16(123), d: &scanstr, wantstr: "123"},
+	{s: uint32(123), d: &scanstr, wantstr: "123"},
+	{s: uint64(123), d: &scanstr, wantstr: "123"},
+	{s: 1.5, d: &scanstr, wantstr: "1.5"},
+
+	// To []byte
+	{s: nil, d: &scanbytes, wantbytes: nil},
+	{s: "string", d: &scanbytes, wantbytes: []byte("string")},
+	{s: []byte("byteslice"), d: &scanbytes, wantbytes: []byte("byteslice")},
+	{s: 123, d: &scanbytes, wantbytes: []byte("123")},
+	{s: int8(123), d: &scanbytes, wantbytes: []byte("123")},
+	{s: int64(123), d: &scanbytes, wantbytes: []byte("123")},
+	{s: uint8(123), d: &scanbytes, wantbytes: []byte("123")},
+	{s: uint16(123), d: &scanbytes, wantbytes: []byte("123")},
+	{s: uint32(123), d: &scanbytes, wantbytes: []byte("123")},
+	{s: uint64(123), d: &scanbytes, wantbytes: []byte("123")},
+	{s: 1.5, d: &scanbytes, wantbytes: []byte("1.5")},
+
+	// To RawBytes
+	{s: nil, d: &scanraw, wantraw: nil},
+	{s: []byte("byteslice"), d: &scanraw, wantraw: RawBytes("byteslice")},
+	{s: 123, d: &scanraw, wantraw: RawBytes("123")},
+	{s: int8(123), d: &scanraw, wantraw: RawBytes("123")},
+	{s: int64(123), d: &scanraw, wantraw: RawBytes("123")},
+	{s: uint8(123), d: &scanraw, wantraw: RawBytes("123")},
+	{s: uint16(123), d: &scanraw, wantraw: RawBytes("123")},
+	{s: uint32(123), d: &scanraw, wantraw: RawBytes("123")},
+	{s: uint64(123), d: &scanraw, wantraw: RawBytes("123")},
+	{s: 1.5, d: &scanraw, wantraw: RawBytes("1.5")},
+
+	// Strings to integers
+	{s: "255", d: &scanuint8, wantuint: 255},
+	{s: "256", d: &scanuint8, wanterr: `converting string "256" to a uint8: strconv.ParseUint: parsing "256": value out of range`},
+	{s: "256", d: &scanuint16, wantuint: 256},
+	{s: "-1", d: &scanint, wantint: -1},
+	{s: "foo", d: &scanint, wanterr: `converting string "foo" to a int: strconv.ParseInt: parsing "foo": invalid syntax`},
+
+	// True bools
+	{s: true, d: &scanbool, wantbool: true},
+	{s: "True", d: &scanbool, wantbool: true},
+	{s: "TRUE", d: &scanbool, wantbool: true},
+	{s: "1", d: &scanbool, wantbool: true},
+	{s: 1, d: &scanbool, wantbool: true},
+	{s: int64(1), d: &scanbool, wantbool: true},
+	{s: uint16(1), d: &scanbool, wantbool: true},
+
+	// False bools
+	{s: false, d: &scanbool, wantbool: false},
+	{s: "false", d: &scanbool, wantbool: false},
+	{s: "FALSE", d: &scanbool, wantbool: false},
+	{s: "0", d: &scanbool, wantbool: false},
+	{s: 0, d: &scanbool, wantbool: false},
+	{s: int64(0), d: &scanbool, wantbool: false},
+	{s: uint16(0), d: &scanbool, wantbool: false},
+
+	// Not bools
+	{s: "yup", d: &scanbool, wanterr: `sql/driver: couldn't convert "yup" into type bool`},
+	{s: 2, d: &scanbool, wanterr: `sql/driver: couldn't convert 2 into type bool`},
+
+	// Floats
+	{s: float64(1.5), d: &scanf64, wantf64: float64(1.5)},
+	{s: int64(1), d: &scanf64, wantf64: float64(1)},
+	{s: float64(1.5), d: &scanf32, wantf32: float32(1.5)},
+	{s: "1.5", d: &scanf32, wantf32: float32(1.5)},
+	{s: "1.5", d: &scanf64, wantf64: float64(1.5)},
+
+	// Pointers
+	{s: interface{}(nil), d: &scanptr, wantnil: true},
+	{s: int64(42), d: &scanptr, wantptr: &answer},
+
+	// To interface{}
+	{s: float64(1.5), d: &scaniface, wantiface: float64(1.5)},
+	{s: int64(1), d: &scaniface, wantiface: int64(1)},
+	{s: "str", d: &scaniface, wantiface: "str"},
+	{s: []byte("byteslice"), d: &scaniface, wantiface: []byte("byteslice")},
+	{s: true, d: &scaniface, wantiface: true},
+	{s: nil, d: &scaniface},
+	{s: []byte(nil), d: &scaniface, wantiface: []byte(nil)},
+}
+
+func intPtrValue(intptr interface{}) interface{} {
+	return reflect.Indirect(reflect.Indirect(reflect.ValueOf(intptr))).Int()
+}
+
+func intValue(intptr interface{}) int64 {
+	return reflect.Indirect(reflect.ValueOf(intptr)).Int()
+}
+
+func uintValue(intptr interface{}) uint64 {
+	return reflect.Indirect(reflect.ValueOf(intptr)).Uint()
+}
+
+func float64Value(ptr interface{}) float64 {
+	return *(ptr.(*float64))
+}
+
+func float32Value(ptr interface{}) float32 {
+	return *(ptr.(*float32))
+}
+
+func timeValue(ptr interface{}) time.Time {
+	return *(ptr.(*time.Time))
+}
+
+func TestConversions(t *testing.T) {
+	for n, ct := range conversionTests {
+		err := convertAssign(ct.d, ct.s)
+		errstr := ""
+		if err != nil {
+			errstr = err.Error()
+		}
+		errf := func(format string, args ...interface{}) {
+			base := fmt.Sprintf("convertAssign #%d: for %v (%T) -> %T, ", n, ct.s, ct.s, ct.d)
+			t.Errorf(base+format, args...)
+		}
+		if errstr != ct.wanterr {
+			errf("got error %q, want error %q", errstr, ct.wanterr)
+		}
+		if ct.wantstr != "" && ct.wantstr != scanstr {
+			errf("want string %q, got %q", ct.wantstr, scanstr)
+		}
+		if ct.wantint != 0 && ct.wantint != intValue(ct.d) {
+			errf("want int %d, got %d", ct.wantint, intValue(ct.d))
+		}
+		if ct.wantuint != 0 && ct.wantuint != uintValue(ct.d) {
+			errf("want uint %d, got %d", ct.wantuint, uintValue(ct.d))
+		}
+		if ct.wantf32 != 0 && ct.wantf32 != float32Value(ct.d) {
+			errf("want float32 %v, got %v", ct.wantf32, float32Value(ct.d))
+		}
+		if ct.wantf64 != 0 && ct.wantf64 != float64Value(ct.d) {
+			errf("want float32 %v, got %v", ct.wantf64, float64Value(ct.d))
+		}
+		if bp, boolTest := ct.d.(*bool); boolTest && *bp != ct.wantbool && ct.wanterr == "" {
+			errf("want bool %v, got %v", ct.wantbool, *bp)
+		}
+		if !ct.wanttime.IsZero() && !ct.wanttime.Equal(timeValue(ct.d)) {
+			errf("want time %v, got %v", ct.wanttime, timeValue(ct.d))
+		}
+		if ct.wantnil && *ct.d.(**int64) != nil {
+			errf("want nil, got %v", intPtrValue(ct.d))
+		}
+		if ct.wantptr != nil {
+			if *ct.d.(**int64) == nil {
+				errf("want pointer to %v, got nil", *ct.wantptr)
+			} else if *ct.wantptr != intPtrValue(ct.d) {
+				errf("want pointer to %v, got %v", *ct.wantptr, intPtrValue(ct.d))
+			}
+		}
+		if ifptr, ok := ct.d.(*interface{}); ok {
+			if !reflect.DeepEqual(ct.wantiface, scaniface) {
+				errf("want interface %#v, got %#v", ct.wantiface, scaniface)
+				continue
+			}
+			if srcBytes, ok := ct.s.([]byte); ok {
+				dstBytes := (*ifptr).([]byte)
+				if len(srcBytes) > 0 && &dstBytes[0] == &srcBytes[0] {
+					errf("copy into interface{} didn't copy []byte data")
+				}
+			}
+		}
+	}
+}
+
+func TestNullString(t *testing.T) {
+	var ns NullString
+	convertAssign(&ns, []byte("foo"))
+	if !ns.Valid {
+		t.Errorf("expecting not null")
+	}
+	if ns.String != "foo" {
+		t.Errorf("expecting foo; got %q", ns.String)
+	}
+	convertAssign(&ns, nil)
+	if ns.Valid {
+		t.Errorf("expecting null on nil")
+	}
+	if ns.String != "" {
+		t.Errorf("expecting blank on nil; got %q", ns.String)
+	}
+}
+
+type valueConverterTest struct {
+	c       driver.ValueConverter
+	in, out interface{}
+	err     string
+}
+
+var valueConverterTests = []valueConverterTest{
+	{driver.DefaultParameterConverter, NullString{"hi", true}, "hi", ""},
+	{driver.DefaultParameterConverter, NullString{"", false}, nil, ""},
+}
+
+func TestValueConverters(t *testing.T) {
+	for i, tt := range valueConverterTests {
+		out, err := tt.c.ConvertValue(tt.in)
+		goterr := ""
+		if err != nil {
+			goterr = err.Error()
+		}
+		if goterr != tt.err {
+			t.Errorf("test %d: %T(%T(%v)) error = %q; want error = %q",
+				i, tt.c, tt.in, tt.in, goterr, tt.err)
+		}
+		if tt.err != "" {
+			continue
+		}
+		if !reflect.DeepEqual(out, tt.out) {
+			t.Errorf("test %d: %T(%T(%v)) = %v (%T); want %v (%T)",
+				i, tt.c, tt.in, tt.in, out, out, tt.out, tt.out)
+		}
+	}
+}
+
+// Tests that assigning to RawBytes doesn't allocate (and also works).
+func TestRawBytesAllocs(t *testing.T) {
+	var tests = []struct {
+		name string
+		in   interface{}
+		want string
+	}{
+		{"uint64", uint64(12345678), "12345678"},
+		{"uint32", uint32(1234), "1234"},
+		{"uint16", uint16(12), "12"},
+		{"uint8", uint8(1), "1"},
+		{"uint", uint(123), "123"},
+		{"int", int(123), "123"},
+		{"int8", int8(1), "1"},
+		{"int16", int16(12), "12"},
+		{"int32", int32(1234), "1234"},
+		{"int64", int64(12345678), "12345678"},
+		{"float32", float32(1.5), "1.5"},
+		{"float64", float64(64), "64"},
+		{"bool", false, "false"},
+	}
+
+	buf := make(RawBytes, 10)
+	test := func(name string, in interface{}, want string) {
+		if err := convertAssign(&buf, in); err != nil {
+			t.Fatalf("%s: convertAssign = %v", name, err)
+		}
+		match := len(buf) == len(want)
+		if match {
+			for i, b := range buf {
+				if want[i] != b {
+					match = false
+					break
+				}
+			}
+		}
+		if !match {
+			t.Fatalf("%s: got %q (len %d); want %q (len %d)", name, buf, len(buf), want, len(want))
+		}
+	}
+
+	n := testing.AllocsPerRun(100, func() {
+		for _, tt := range tests {
+			test(tt.name, tt.in, tt.want)
+		}
+	})
+
+	// The numbers below are only valid for 64-bit interface word sizes,
+	// and gc. With 32-bit words there are more convT2E allocs, and
+	// with gccgo, only pointers currently go in interface data.
+	// So only care on amd64 gc for now.
+	measureAllocs := runtime.GOARCH == "amd64" && runtime.Compiler == "gc"
+
+	if n > 0.5 && measureAllocs {
+		t.Fatalf("allocs = %v; want 0", n)
+	}
+
+	// This one involves a convT2E allocation, string -> interface{}
+	n = testing.AllocsPerRun(100, func() {
+		test("string", "foo", "foo")
+	})
+	if n > 1.5 && measureAllocs {
+		t.Fatalf("allocs = %v; want max 1", n)
+	}
+}
diff --git a/src/database/sql/doc.txt b/src/database/sql/doc.txt
new file mode 100644
index 000000000..405c5ed2a
--- /dev/null
+++ b/src/database/sql/doc.txt
@@ -0,0 +1,46 @@
+Goals of the sql and sql/driver packages:
+
+* Provide a generic database API for a variety of SQL or SQL-like
+  databases.  There currently exist Go libraries for SQLite, MySQL,
+  and Postgres, but all with a very different feel, and often
+  a non-Go-like feel.
+
+* Feel like Go.
+
+* Care mostly about the common cases. Common SQL should be portable.
+  SQL edge cases or db-specific extensions can be detected and
+  conditionally used by the application.  It is a non-goal to care
+  about every particular db's extension or quirk.
+
+* Separate out the basic implementation of a database driver
+  (implementing the sql/driver interfaces) vs the implementation
+  of all the user-level types and convenience methods.
+  In a nutshell:
+
+  User Code ---> sql package (concrete types) ---> sql/driver (interfaces)
+  Database Driver -> sql (to register) + sql/driver (implement interfaces)
+
+* Make type casting/conversions consistent between all drivers. To
+  achieve this, most of the conversions are done in the sql package,
+  not in each driver. The drivers then only have to deal with a
+  smaller set of types.
+
+* Be flexible with type conversions, but be paranoid about silent
+  truncation or other loss of precision.
+
+* Handle concurrency well.  Users shouldn't need to care about the
+  database's per-connection thread safety issues (or lack thereof),
+  and shouldn't have to maintain their own free pools of connections.
+  The 'db' package should deal with that bookkeeping as needed.  Given
+  an *sql.DB, it should be possible to share that instance between
+  multiple goroutines, without any extra synchronization.
+
+* Push complexity, where necessary, down into the sql+driver packages,
+  rather than exposing it to users. Said otherwise, the sql package
+  should expose an ideal database that's not finnicky about how it's
+  accessed, even if that's not true.
+
+* Provide optional interfaces in sql/driver for drivers to implement
+  for special cases or fastpaths.  But the only party that knows about
+  those is the sql package.  To user code, some stuff just might start
+  working or start working slightly faster.
diff --git a/src/database/sql/driver/driver.go b/src/database/sql/driver/driver.go
new file mode 100644
index 000000000..eca25f29a
--- /dev/null
+++ b/src/database/sql/driver/driver.go
@@ -0,0 +1,211 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package driver defines interfaces to be implemented by database
+// drivers as used by package sql.
+//
+// Most code should use package sql.
+package driver
+
+import "errors"
+
+// Value is a value that drivers must be able to handle.
+// It is either nil or an instance of one of these types:
+//
+//   int64
+//   float64
+//   bool
+//   []byte
+//   string   [*] everywhere except from Rows.Next.
+//   time.Time
+type Value interface{}
+
+// Driver is the interface that must be implemented by a database
+// driver.
+type Driver interface {
+	// Open returns a new connection to the database.
+	// The name is a string in a driver-specific format.
+	//
+	// Open may return a cached connection (one previously
+	// closed), but doing so is unnecessary; the sql package
+	// maintains a pool of idle connections for efficient re-use.
+	//
+	// The returned connection is only used by one goroutine at a
+	// time.
+	Open(name string) (Conn, error)
+}
+
+// ErrSkip may be returned by some optional interfaces' methods to
+// indicate at runtime that the fast path is unavailable and the sql
+// package should continue as if the optional interface was not
+// implemented. ErrSkip is only supported where explicitly
+// documented.
+var ErrSkip = errors.New("driver: skip fast-path; continue as if unimplemented")
+
+// ErrBadConn should be returned by a driver to signal to the sql
+// package that a driver.Conn is in a bad state (such as the server
+// having earlier closed the connection) and the sql package should
+// retry on a new connection.
+//
+// To prevent duplicate operations, ErrBadConn should NOT be returned
+// if there's a possibility that the database server might have
+// performed the operation. Even if the server sends back an error,
+// you shouldn't return ErrBadConn.
+var ErrBadConn = errors.New("driver: bad connection")
+
+// Execer is an optional interface that may be implemented by a Conn.
+//
+// If a Conn does not implement Execer, the sql package's DB.Exec will
+// first prepare a query, execute the statement, and then close the
+// statement.
+//
+// Exec may return ErrSkip.
+type Execer interface {
+	Exec(query string, args []Value) (Result, error)
+}
+
+// Queryer is an optional interface that may be implemented by a Conn.
+//
+// If a Conn does not implement Queryer, the sql package's DB.Query will
+// first prepare a query, execute the statement, and then close the
+// statement.
+//
+// Query may return ErrSkip.
+type Queryer interface {
+	Query(query string, args []Value) (Rows, error)
+}
+
+// Conn is a connection to a database. It is not used concurrently
+// by multiple goroutines.
+//
+// Conn is assumed to be stateful.
+type Conn interface {
+	// Prepare returns a prepared statement, bound to this connection.
+	Prepare(query string) (Stmt, error)
+
+	// Close invalidates and potentially stops any current
+	// prepared statements and transactions, marking this
+	// connection as no longer in use.
+	//
+	// Because the sql package maintains a free pool of
+	// connections and only calls Close when there's a surplus of
+	// idle connections, it shouldn't be necessary for drivers to
+	// do their own connection caching.
+	Close() error
+
+	// Begin starts and returns a new transaction.
+	Begin() (Tx, error)
+}
+
+// Result is the result of a query execution.
+type Result interface {
+	// LastInsertId returns the database's auto-generated ID
+	// after, for example, an INSERT into a table with primary
+	// key.
+	LastInsertId() (int64, error)
+
+	// RowsAffected returns the number of rows affected by the
+	// query.
+	RowsAffected() (int64, error)
+}
+
+// Stmt is a prepared statement. It is bound to a Conn and not
+// used by multiple goroutines concurrently.
+type Stmt interface {
+	// Close closes the statement.
+	//
+	// As of Go 1.1, a Stmt will not be closed if it's in use
+	// by any queries.
+	Close() error
+
+	// NumInput returns the number of placeholder parameters.
+	//
+	// If NumInput returns >= 0, the sql package will sanity check
+	// argument counts from callers and return errors to the caller
+	// before the statement's Exec or Query methods are called.
+	//
+	// NumInput may also return -1, if the driver doesn't know
+	// its number of placeholders. In that case, the sql package
+	// will not sanity check Exec or Query argument counts.
+	NumInput() int
+
+	// Exec executes a query that doesn't return rows, such
+	// as an INSERT or UPDATE.
+	Exec(args []Value) (Result, error)
+
+	// Query executes a query that may return rows, such as a
+	// SELECT.
+	Query(args []Value) (Rows, error)
+}
+
+// ColumnConverter may be optionally implemented by Stmt if the
+// statement is aware of its own columns' types and can convert from
+// any type to a driver Value.
+type ColumnConverter interface {
+	// ColumnConverter returns a ValueConverter for the provided
+	// column index.  If the type of a specific column isn't known
+	// or shouldn't be handled specially, DefaultValueConverter
+	// can be returned.
+	ColumnConverter(idx int) ValueConverter
+}
+
+// Rows is an iterator over an executed query's results.
+type Rows interface {
+	// Columns returns the names of the columns. The number of
+	// columns of the result is inferred from the length of the
+	// slice.  If a particular column name isn't known, an empty
+	// string should be returned for that entry.
+	Columns() []string
+
+	// Close closes the rows iterator.
+	Close() error
+
+	// Next is called to populate the next row of data into
+	// the provided slice. The provided slice will be the same
+	// size as the Columns() are wide.
+	//
+	// The dest slice may be populated only with
+	// a driver Value type, but excluding string.
+	// All string values must be converted to []byte.
+	//
+	// Next should return io.EOF when there are no more rows.
+	Next(dest []Value) error
+}
+
+// Tx is a transaction.
+type Tx interface {
+	Commit() error
+	Rollback() error
+}
+
+// RowsAffected implements Result for an INSERT or UPDATE operation
+// which mutates a number of rows.
+type RowsAffected int64
+
+var _ Result = RowsAffected(0)
+
+func (RowsAffected) LastInsertId() (int64, error) {
+	return 0, errors.New("no LastInsertId available")
+}
+
+func (v RowsAffected) RowsAffected() (int64, error) {
+	return int64(v), nil
+}
+
+// ResultNoRows is a pre-defined Result for drivers to return when a DDL
+// command (such as a CREATE TABLE) succeeds. It returns an error for both
+// LastInsertId and RowsAffected.
+var ResultNoRows noRows
+
+type noRows struct{}
+
+var _ Result = noRows{}
+
+func (noRows) LastInsertId() (int64, error) {
+	return 0, errors.New("no LastInsertId available after DDL statement")
+}
+
+func (noRows) RowsAffected() (int64, error) {
+	return 0, errors.New("no RowsAffected available after DDL statement")
+}
diff --git a/src/database/sql/driver/types.go b/src/database/sql/driver/types.go
new file mode 100644
index 000000000..3305354df
--- /dev/null
+++ b/src/database/sql/driver/types.go
@@ -0,0 +1,252 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package driver
+
+import (
+	"fmt"
+	"reflect"
+	"strconv"
+	"time"
+)
+
+// ValueConverter is the interface providing the ConvertValue method.
+//
+// Various implementations of ValueConverter are provided by the
+// driver package to provide consistent implementations of conversions
+// between drivers.  The ValueConverters have several uses:
+//
+//  * converting from the Value types as provided by the sql package
+//    into a database table's specific column type and making sure it
+//    fits, such as making sure a particular int64 fits in a
+//    table's uint16 column.
+//
+//  * converting a value as given from the database into one of the
+//    driver Value types.
+//
+//  * by the sql package, for converting from a driver's Value type
+//    to a user's type in a scan.
+type ValueConverter interface {
+	// ConvertValue converts a value to a driver Value.
+	ConvertValue(v interface{}) (Value, error)
+}
+
+// Valuer is the interface providing the Value method.
+//
+// Types implementing Valuer interface are able to convert
+// themselves to a driver Value.
+type Valuer interface {
+	// Value returns a driver Value.
+	Value() (Value, error)
+}
+
+// Bool is a ValueConverter that converts input values to bools.
+//
+// The conversion rules are:
+//  - booleans are returned unchanged
+//  - for integer types,
+//       1 is true
+//       0 is false,
+//       other integers are an error
+//  - for strings and []byte, same rules as strconv.ParseBool
+//  - all other types are an error
+var Bool boolType
+
+type boolType struct{}
+
+var _ ValueConverter = boolType{}
+
+func (boolType) String() string { return "Bool" }
+
+func (boolType) ConvertValue(src interface{}) (Value, error) {
+	switch s := src.(type) {
+	case bool:
+		return s, nil
+	case string:
+		b, err := strconv.ParseBool(s)
+		if err != nil {
+			return nil, fmt.Errorf("sql/driver: couldn't convert %q into type bool", s)
+		}
+		return b, nil
+	case []byte:
+		b, err := strconv.ParseBool(string(s))
+		if err != nil {
+			return nil, fmt.Errorf("sql/driver: couldn't convert %q into type bool", s)
+		}
+		return b, nil
+	}
+
+	sv := reflect.ValueOf(src)
+	switch sv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		iv := sv.Int()
+		if iv == 1 || iv == 0 {
+			return iv == 1, nil
+		}
+		return nil, fmt.Errorf("sql/driver: couldn't convert %d into type bool", iv)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		uv := sv.Uint()
+		if uv == 1 || uv == 0 {
+			return uv == 1, nil
+		}
+		return nil, fmt.Errorf("sql/driver: couldn't convert %d into type bool", uv)
+	}
+
+	return nil, fmt.Errorf("sql/driver: couldn't convert %v (%T) into type bool", src, src)
+}
+
+// Int32 is a ValueConverter that converts input values to int64,
+// respecting the limits of an int32 value.
+var Int32 int32Type
+
+type int32Type struct{}
+
+var _ ValueConverter = int32Type{}
+
+func (int32Type) ConvertValue(v interface{}) (Value, error) {
+	rv := reflect.ValueOf(v)
+	switch rv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		i64 := rv.Int()
+		if i64 > (1<<31)-1 || i64 < -(1<<31) {
+			return nil, fmt.Errorf("sql/driver: value %d overflows int32", v)
+		}
+		return i64, nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		u64 := rv.Uint()
+		if u64 > (1<<31)-1 {
+			return nil, fmt.Errorf("sql/driver: value %d overflows int32", v)
+		}
+		return int64(u64), nil
+	case reflect.String:
+		i, err := strconv.Atoi(rv.String())
+		if err != nil {
+			return nil, fmt.Errorf("sql/driver: value %q can't be converted to int32", v)
+		}
+		return int64(i), nil
+	}
+	return nil, fmt.Errorf("sql/driver: unsupported value %v (type %T) converting to int32", v, v)
+}
+
+// String is a ValueConverter that converts its input to a string.
+// If the value is already a string or []byte, it's unchanged.
+// If the value is of another type, conversion to string is done
+// with fmt.Sprintf("%v", v).
+var String stringType
+
+type stringType struct{}
+
+func (stringType) ConvertValue(v interface{}) (Value, error) {
+	switch v.(type) {
+	case string, []byte:
+		return v, nil
+	}
+	return fmt.Sprintf("%v", v), nil
+}
+
+// Null is a type that implements ValueConverter by allowing nil
+// values but otherwise delegating to another ValueConverter.
+type Null struct {
+	Converter ValueConverter
+}
+
+func (n Null) ConvertValue(v interface{}) (Value, error) {
+	if v == nil {
+		return nil, nil
+	}
+	return n.Converter.ConvertValue(v)
+}
+
+// NotNull is a type that implements ValueConverter by disallowing nil
+// values but otherwise delegating to another ValueConverter.
+type NotNull struct {
+	Converter ValueConverter
+}
+
+func (n NotNull) ConvertValue(v interface{}) (Value, error) {
+	if v == nil {
+		return nil, fmt.Errorf("nil value not allowed")
+	}
+	return n.Converter.ConvertValue(v)
+}
+
+// IsValue reports whether v is a valid Value parameter type.
+// Unlike IsScanValue, IsValue permits the string type.
+func IsValue(v interface{}) bool {
+	if IsScanValue(v) {
+		return true
+	}
+	if _, ok := v.(string); ok {
+		return true
+	}
+	return false
+}
+
+// IsScanValue reports whether v is a valid Value scan type.
+// Unlike IsValue, IsScanValue does not permit the string type.
+func IsScanValue(v interface{}) bool {
+	if v == nil {
+		return true
+	}
+	switch v.(type) {
+	case int64, float64, []byte, bool, time.Time:
+		return true
+	}
+	return false
+}
+
+// DefaultParameterConverter is the default implementation of
+// ValueConverter that's used when a Stmt doesn't implement
+// ColumnConverter.
+//
+// DefaultParameterConverter returns the given value directly if
+// IsValue(value).  Otherwise integer type are converted to
+// int64, floats to float64, and strings to []byte.  Other types are
+// an error.
+var DefaultParameterConverter defaultConverter
+
+type defaultConverter struct{}
+
+var _ ValueConverter = defaultConverter{}
+
+func (defaultConverter) ConvertValue(v interface{}) (Value, error) {
+	if IsValue(v) {
+		return v, nil
+	}
+
+	if svi, ok := v.(Valuer); ok {
+		sv, err := svi.Value()
+		if err != nil {
+			return nil, err
+		}
+		if !IsValue(sv) {
+			return nil, fmt.Errorf("non-Value type %T returned from Value", sv)
+		}
+		return sv, nil
+	}
+
+	rv := reflect.ValueOf(v)
+	switch rv.Kind() {
+	case reflect.Ptr:
+		// indirect pointers
+		if rv.IsNil() {
+			return nil, nil
+		} else {
+			return defaultConverter{}.ConvertValue(rv.Elem().Interface())
+		}
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return rv.Int(), nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32:
+		return int64(rv.Uint()), nil
+	case reflect.Uint64:
+		u64 := rv.Uint()
+		if u64 >= 1<<63 {
+			return nil, fmt.Errorf("uint64 values with high bit set are not supported")
+		}
+		return int64(u64), nil
+	case reflect.Float32, reflect.Float64:
+		return rv.Float(), nil
+	}
+	return nil, fmt.Errorf("unsupported type %T, a %s", v, rv.Kind())
+}
diff --git a/src/database/sql/driver/types_test.go b/src/database/sql/driver/types_test.go
new file mode 100644
index 000000000..1ce0ff065
--- /dev/null
+++ b/src/database/sql/driver/types_test.go
@@ -0,0 +1,65 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package driver
+
+import (
+	"reflect"
+	"testing"
+	"time"
+)
+
+type valueConverterTest struct {
+	c   ValueConverter
+	in  interface{}
+	out interface{}
+	err string
+}
+
+var now = time.Now()
+var answer int64 = 42
+
+var valueConverterTests = []valueConverterTest{
+	{Bool, "true", true, ""},
+	{Bool, "True", true, ""},
+	{Bool, []byte("t"), true, ""},
+	{Bool, true, true, ""},
+	{Bool, "1", true, ""},
+	{Bool, 1, true, ""},
+	{Bool, int64(1), true, ""},
+	{Bool, uint16(1), true, ""},
+	{Bool, "false", false, ""},
+	{Bool, false, false, ""},
+	{Bool, "0", false, ""},
+	{Bool, 0, false, ""},
+	{Bool, int64(0), false, ""},
+	{Bool, uint16(0), false, ""},
+	{c: Bool, in: "foo", err: "sql/driver: couldn't convert \"foo\" into type bool"},
+	{c: Bool, in: 2, err: "sql/driver: couldn't convert 2 into type bool"},
+	{DefaultParameterConverter, now, now, ""},
+	{DefaultParameterConverter, (*int64)(nil), nil, ""},
+	{DefaultParameterConverter, &answer, answer, ""},
+	{DefaultParameterConverter, &now, now, ""},
+}
+
+func TestValueConverters(t *testing.T) {
+	for i, tt := range valueConverterTests {
+		out, err := tt.c.ConvertValue(tt.in)
+		goterr := ""
+		if err != nil {
+			goterr = err.Error()
+		}
+		if goterr != tt.err {
+			t.Errorf("test %d: %T(%T(%v)) error = %q; want error = %q",
+				i, tt.c, tt.in, tt.in, goterr, tt.err)
+		}
+		if tt.err != "" {
+			continue
+		}
+		if !reflect.DeepEqual(out, tt.out) {
+			t.Errorf("test %d: %T(%T(%v)) = %v (%T); want %v (%T)",
+				i, tt.c, tt.in, tt.in, out, out, tt.out, tt.out)
+		}
+	}
+}
diff --git a/src/database/sql/example_test.go b/src/database/sql/example_test.go
new file mode 100644
index 000000000..dcb74e069
--- /dev/null
+++ b/src/database/sql/example_test.go
@@ -0,0 +1,46 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sql_test
+
+import (
+	"database/sql"
+	"fmt"
+	"log"
+)
+
+var db *sql.DB
+
+func ExampleDB_Query() {
+	age := 27
+	rows, err := db.Query("SELECT name FROM users WHERE age=?", age)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var name string
+		if err := rows.Scan(&name); err != nil {
+			log.Fatal(err)
+		}
+		fmt.Printf("%s is %d\n", name, age)
+	}
+	if err := rows.Err(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func ExampleDB_QueryRow() {
+	id := 123
+	var username string
+	err := db.QueryRow("SELECT username FROM users WHERE id=?", id).Scan(&username)
+	switch {
+	case err == sql.ErrNoRows:
+		log.Printf("No user with that ID.")
+	case err != nil:
+		log.Fatal(err)
+	default:
+		fmt.Printf("Username is %s\n", username)
+	}
+}
diff --git a/src/database/sql/fakedb_test.go b/src/database/sql/fakedb_test.go
new file mode 100644
index 000000000..c7db0dd77
--- /dev/null
+++ b/src/database/sql/fakedb_test.go
@@ -0,0 +1,805 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sql
+
+import (
+	"database/sql/driver"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"strconv"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+)
+
+var _ = log.Printf
+
+// fakeDriver is a fake database that implements Go's driver.Driver
+// interface, just for testing.
+//
+// It speaks a query language that's semantically similar to but
+// syntactically different and simpler than SQL.  The syntax is as
+// follows:
+//
+//   WIPE
+//   CREATE|<tablename>|<col>=<type>,<col>=<type>,...
+//     where types are: "string", [u]int{8,16,32,64}, "bool"
+//   INSERT|<tablename>|col=val,col2=val2,col3=?
+//   SELECT|<tablename>|projectcol1,projectcol2|filtercol=?,filtercol2=?
+//
+// When opening a fakeDriver's database, it starts empty with no
+// tables.  All tables and data are stored in memory only.
+type fakeDriver struct {
+	mu         sync.Mutex // guards 3 following fields
+	openCount  int        // conn opens
+	closeCount int        // conn closes
+	waitCh     chan struct{}
+	waitingCh  chan struct{}
+	dbs        map[string]*fakeDB
+}
+
+type fakeDB struct {
+	name string
+
+	mu      sync.Mutex
+	free    []*fakeConn
+	tables  map[string]*table
+	badConn bool
+}
+
+type table struct {
+	mu      sync.Mutex
+	colname []string
+	coltype []string
+	rows    []*row
+}
+
+func (t *table) columnIndex(name string) int {
+	for n, nname := range t.colname {
+		if name == nname {
+			return n
+		}
+	}
+	return -1
+}
+
+type row struct {
+	cols []interface{} // must be same size as its table colname + coltype
+}
+
+func (r *row) clone() *row {
+	nrow := &row{cols: make([]interface{}, len(r.cols))}
+	copy(nrow.cols, r.cols)
+	return nrow
+}
+
+type fakeConn struct {
+	db *fakeDB // where to return ourselves to
+
+	currTx *fakeTx
+
+	// Stats for tests:
+	mu          sync.Mutex
+	stmtsMade   int
+	stmtsClosed int
+	numPrepare  int
+	bad         bool
+}
+
+func (c *fakeConn) incrStat(v *int) {
+	c.mu.Lock()
+	*v++
+	c.mu.Unlock()
+}
+
+type fakeTx struct {
+	c *fakeConn
+}
+
+type fakeStmt struct {
+	c *fakeConn
+	q string // just for debugging
+
+	cmd   string
+	table string
+
+	closed bool
+
+	colName      []string      // used by CREATE, INSERT, SELECT (selected columns)
+	colType      []string      // used by CREATE
+	colValue     []interface{} // used by INSERT (mix of strings and "?" for bound params)
+	placeholders int           // used by INSERT/SELECT: number of ? params
+
+	whereCol []string // used by SELECT (all placeholders)
+
+	placeholderConverter []driver.ValueConverter // used by INSERT
+}
+
+var fdriver driver.Driver = &fakeDriver{}
+
+func init() {
+	Register("test", fdriver)
+}
+
+// Supports dsn forms:
+//    <dbname>
+//    <dbname>;<opts>  (only currently supported option is `badConn`,
+//                      which causes driver.ErrBadConn to be returned on
+//                      every other conn.Begin())
+func (d *fakeDriver) Open(dsn string) (driver.Conn, error) {
+	parts := strings.Split(dsn, ";")
+	if len(parts) < 1 {
+		return nil, errors.New("fakedb: no database name")
+	}
+	name := parts[0]
+
+	db := d.getDB(name)
+
+	d.mu.Lock()
+	d.openCount++
+	d.mu.Unlock()
+	conn := &fakeConn{db: db}
+
+	if len(parts) >= 2 && parts[1] == "badConn" {
+		conn.bad = true
+	}
+	if d.waitCh != nil {
+		d.waitingCh <- struct{}{}
+		<-d.waitCh
+		d.waitCh = nil
+		d.waitingCh = nil
+	}
+	return conn, nil
+}
+
+func (d *fakeDriver) getDB(name string) *fakeDB {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	if d.dbs == nil {
+		d.dbs = make(map[string]*fakeDB)
+	}
+	db, ok := d.dbs[name]
+	if !ok {
+		db = &fakeDB{name: name}
+		d.dbs[name] = db
+	}
+	return db
+}
+
+func (db *fakeDB) wipe() {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	db.tables = nil
+}
+
+func (db *fakeDB) createTable(name string, columnNames, columnTypes []string) error {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	if db.tables == nil {
+		db.tables = make(map[string]*table)
+	}
+	if _, exist := db.tables[name]; exist {
+		return fmt.Errorf("table %q already exists", name)
+	}
+	if len(columnNames) != len(columnTypes) {
+		return fmt.Errorf("create table of %q len(names) != len(types): %d vs %d",
+			name, len(columnNames), len(columnTypes))
+	}
+	db.tables[name] = &table{colname: columnNames, coltype: columnTypes}
+	return nil
+}
+
+// must be called with db.mu lock held
+func (db *fakeDB) table(table string) (*table, bool) {
+	if db.tables == nil {
+		return nil, false
+	}
+	t, ok := db.tables[table]
+	return t, ok
+}
+
+func (db *fakeDB) columnType(table, column string) (typ string, ok bool) {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	t, ok := db.table(table)
+	if !ok {
+		return
+	}
+	for n, cname := range t.colname {
+		if cname == column {
+			return t.coltype[n], true
+		}
+	}
+	return "", false
+}
+
+func (c *fakeConn) isBad() bool {
+	// if not simulating bad conn, do nothing
+	if !c.bad {
+		return false
+	}
+	// alternate between bad conn and not bad conn
+	c.db.badConn = !c.db.badConn
+	return c.db.badConn
+}
+
+func (c *fakeConn) Begin() (driver.Tx, error) {
+	if c.isBad() {
+		return nil, driver.ErrBadConn
+	}
+	if c.currTx != nil {
+		return nil, errors.New("already in a transaction")
+	}
+	c.currTx = &fakeTx{c: c}
+	return c.currTx, nil
+}
+
+var hookPostCloseConn struct {
+	sync.Mutex
+	fn func(*fakeConn, error)
+}
+
+func setHookpostCloseConn(fn func(*fakeConn, error)) {
+	hookPostCloseConn.Lock()
+	defer hookPostCloseConn.Unlock()
+	hookPostCloseConn.fn = fn
+}
+
+var testStrictClose *testing.T
+
+// setStrictFakeConnClose sets the t to Errorf on when fakeConn.Close
+// fails to close. If nil, the check is disabled.
+func setStrictFakeConnClose(t *testing.T) {
+	testStrictClose = t
+}
+
+func (c *fakeConn) Close() (err error) {
+	drv := fdriver.(*fakeDriver)
+	defer func() {
+		if err != nil && testStrictClose != nil {
+			testStrictClose.Errorf("failed to close a test fakeConn: %v", err)
+		}
+		hookPostCloseConn.Lock()
+		fn := hookPostCloseConn.fn
+		hookPostCloseConn.Unlock()
+		if fn != nil {
+			fn(c, err)
+		}
+		if err == nil {
+			drv.mu.Lock()
+			drv.closeCount++
+			drv.mu.Unlock()
+		}
+	}()
+	if c.currTx != nil {
+		return errors.New("can't close fakeConn; in a Transaction")
+	}
+	if c.db == nil {
+		return errors.New("can't close fakeConn; already closed")
+	}
+	if c.stmtsMade > c.stmtsClosed {
+		return errors.New("can't close; dangling statement(s)")
+	}
+	c.db = nil
+	return nil
+}
+
+func checkSubsetTypes(args []driver.Value) error {
+	for n, arg := range args {
+		switch arg.(type) {
+		case int64, float64, bool, nil, []byte, string, time.Time:
+		default:
+			return fmt.Errorf("fakedb_test: invalid argument #%d: %v, type %T", n+1, arg, arg)
+		}
+	}
+	return nil
+}
+
+func (c *fakeConn) Exec(query string, args []driver.Value) (driver.Result, error) {
+	// This is an optional interface, but it's implemented here
+	// just to check that all the args are of the proper types.
+	// ErrSkip is returned so the caller acts as if we didn't
+	// implement this at all.
+	err := checkSubsetTypes(args)
+	if err != nil {
+		return nil, err
+	}
+	return nil, driver.ErrSkip
+}
+
+func (c *fakeConn) Query(query string, args []driver.Value) (driver.Rows, error) {
+	// This is an optional interface, but it's implemented here
+	// just to check that all the args are of the proper types.
+	// ErrSkip is returned so the caller acts as if we didn't
+	// implement this at all.
+	err := checkSubsetTypes(args)
+	if err != nil {
+		return nil, err
+	}
+	return nil, driver.ErrSkip
+}
+
+func errf(msg string, args ...interface{}) error {
+	return errors.New("fakedb: " + fmt.Sprintf(msg, args...))
+}
+
+// parts are table|selectCol1,selectCol2|whereCol=?,whereCol2=?
+// (note that where columns must always contain ? marks,
+//  just a limitation for fakedb)
+func (c *fakeConn) prepareSelect(stmt *fakeStmt, parts []string) (driver.Stmt, error) {
+	if len(parts) != 3 {
+		stmt.Close()
+		return nil, errf("invalid SELECT syntax with %d parts; want 3", len(parts))
+	}
+	stmt.table = parts[0]
+	stmt.colName = strings.Split(parts[1], ",")
+	for n, colspec := range strings.Split(parts[2], ",") {
+		if colspec == "" {
+			continue
+		}
+		nameVal := strings.Split(colspec, "=")
+		if len(nameVal) != 2 {
+			stmt.Close()
+			return nil, errf("SELECT on table %q has invalid column spec of %q (index %d)", stmt.table, colspec, n)
+		}
+		column, value := nameVal[0], nameVal[1]
+		_, ok := c.db.columnType(stmt.table, column)
+		if !ok {
+			stmt.Close()
+			return nil, errf("SELECT on table %q references non-existent column %q", stmt.table, column)
+		}
+		if value != "?" {
+			stmt.Close()
+			return nil, errf("SELECT on table %q has pre-bound value for where column %q; need a question mark",
+				stmt.table, column)
+		}
+		stmt.whereCol = append(stmt.whereCol, column)
+		stmt.placeholders++
+	}
+	return stmt, nil
+}
+
+// parts are table|col=type,col2=type2
+func (c *fakeConn) prepareCreate(stmt *fakeStmt, parts []string) (driver.Stmt, error) {
+	if len(parts) != 2 {
+		stmt.Close()
+		return nil, errf("invalid CREATE syntax with %d parts; want 2", len(parts))
+	}
+	stmt.table = parts[0]
+	for n, colspec := range strings.Split(parts[1], ",") {
+		nameType := strings.Split(colspec, "=")
+		if len(nameType) != 2 {
+			stmt.Close()
+			return nil, errf("CREATE table %q has invalid column spec of %q (index %d)", stmt.table, colspec, n)
+		}
+		stmt.colName = append(stmt.colName, nameType[0])
+		stmt.colType = append(stmt.colType, nameType[1])
+	}
+	return stmt, nil
+}
+
+// parts are table|col=?,col2=val
+func (c *fakeConn) prepareInsert(stmt *fakeStmt, parts []string) (driver.Stmt, error) {
+	if len(parts) != 2 {
+		stmt.Close()
+		return nil, errf("invalid INSERT syntax with %d parts; want 2", len(parts))
+	}
+	stmt.table = parts[0]
+	for n, colspec := range strings.Split(parts[1], ",") {
+		nameVal := strings.Split(colspec, "=")
+		if len(nameVal) != 2 {
+			stmt.Close()
+			return nil, errf("INSERT table %q has invalid column spec of %q (index %d)", stmt.table, colspec, n)
+		}
+		column, value := nameVal[0], nameVal[1]
+		ctype, ok := c.db.columnType(stmt.table, column)
+		if !ok {
+			stmt.Close()
+			return nil, errf("INSERT table %q references non-existent column %q", stmt.table, column)
+		}
+		stmt.colName = append(stmt.colName, column)
+
+		if value != "?" {
+			var subsetVal interface{}
+			// Convert to driver subset type
+			switch ctype {
+			case "string":
+				subsetVal = []byte(value)
+			case "blob":
+				subsetVal = []byte(value)
+			case "int32":
+				i, err := strconv.Atoi(value)
+				if err != nil {
+					stmt.Close()
+					return nil, errf("invalid conversion to int32 from %q", value)
+				}
+				subsetVal = int64(i) // int64 is a subset type, but not int32
+			default:
+				stmt.Close()
+				return nil, errf("unsupported conversion for pre-bound parameter %q to type %q", value, ctype)
+			}
+			stmt.colValue = append(stmt.colValue, subsetVal)
+		} else {
+			stmt.placeholders++
+			stmt.placeholderConverter = append(stmt.placeholderConverter, converterForType(ctype))
+			stmt.colValue = append(stmt.colValue, "?")
+		}
+	}
+	return stmt, nil
+}
+
+// hook to simulate broken connections
+var hookPrepareBadConn func() bool
+
+func (c *fakeConn) Prepare(query string) (driver.Stmt, error) {
+	c.numPrepare++
+	if c.db == nil {
+		panic("nil c.db; conn = " + fmt.Sprintf("%#v", c))
+	}
+
+	if hookPrepareBadConn != nil && hookPrepareBadConn() {
+		return nil, driver.ErrBadConn
+	}
+
+	parts := strings.Split(query, "|")
+	if len(parts) < 1 {
+		return nil, errf("empty query")
+	}
+	cmd := parts[0]
+	parts = parts[1:]
+	stmt := &fakeStmt{q: query, c: c, cmd: cmd}
+	c.incrStat(&c.stmtsMade)
+	switch cmd {
+	case "WIPE":
+		// Nothing
+	case "SELECT":
+		return c.prepareSelect(stmt, parts)
+	case "CREATE":
+		return c.prepareCreate(stmt, parts)
+	case "INSERT":
+		return c.prepareInsert(stmt, parts)
+	case "NOSERT":
+		// Do all the prep-work like for an INSERT but don't actually insert the row.
+		// Used for some of the concurrent tests.
+		return c.prepareInsert(stmt, parts)
+	default:
+		stmt.Close()
+		return nil, errf("unsupported command type %q", cmd)
+	}
+	return stmt, nil
+}
+
+func (s *fakeStmt) ColumnConverter(idx int) driver.ValueConverter {
+	if len(s.placeholderConverter) == 0 {
+		return driver.DefaultParameterConverter
+	}
+	return s.placeholderConverter[idx]
+}
+
+func (s *fakeStmt) Close() error {
+	if s.c == nil {
+		panic("nil conn in fakeStmt.Close")
+	}
+	if s.c.db == nil {
+		panic("in fakeStmt.Close, conn's db is nil (already closed)")
+	}
+	if !s.closed {
+		s.c.incrStat(&s.c.stmtsClosed)
+		s.closed = true
+	}
+	return nil
+}
+
+var errClosed = errors.New("fakedb: statement has been closed")
+
+// hook to simulate broken connections
+var hookExecBadConn func() bool
+
+func (s *fakeStmt) Exec(args []driver.Value) (driver.Result, error) {
+	if s.closed {
+		return nil, errClosed
+	}
+
+	if hookExecBadConn != nil && hookExecBadConn() {
+		return nil, driver.ErrBadConn
+	}
+
+	err := checkSubsetTypes(args)
+	if err != nil {
+		return nil, err
+	}
+
+	db := s.c.db
+	switch s.cmd {
+	case "WIPE":
+		db.wipe()
+		return driver.ResultNoRows, nil
+	case "CREATE":
+		if err := db.createTable(s.table, s.colName, s.colType); err != nil {
+			return nil, err
+		}
+		return driver.ResultNoRows, nil
+	case "INSERT":
+		return s.execInsert(args, true)
+	case "NOSERT":
+		// Do all the prep-work like for an INSERT but don't actually insert the row.
+		// Used for some of the concurrent tests.
+		return s.execInsert(args, false)
+	}
+	fmt.Printf("EXEC statement, cmd=%q: %#v\n", s.cmd, s)
+	return nil, fmt.Errorf("unimplemented statement Exec command type of %q", s.cmd)
+}
+
+// When doInsert is true, add the row to the table.
+// When doInsert is false do prep-work and error checking, but don't
+// actually add the row to the table.
+func (s *fakeStmt) execInsert(args []driver.Value, doInsert bool) (driver.Result, error) {
+	db := s.c.db
+	if len(args) != s.placeholders {
+		panic("error in pkg db; should only get here if size is correct")
+	}
+	db.mu.Lock()
+	t, ok := db.table(s.table)
+	db.mu.Unlock()
+	if !ok {
+		return nil, fmt.Errorf("fakedb: table %q doesn't exist", s.table)
+	}
+
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	var cols []interface{}
+	if doInsert {
+		cols = make([]interface{}, len(t.colname))
+	}
+	argPos := 0
+	for n, colname := range s.colName {
+		colidx := t.columnIndex(colname)
+		if colidx == -1 {
+			return nil, fmt.Errorf("fakedb: column %q doesn't exist or dropped since prepared statement was created", colname)
+		}
+		var val interface{}
+		if strvalue, ok := s.colValue[n].(string); ok && strvalue == "?" {
+			val = args[argPos]
+			argPos++
+		} else {
+			val = s.colValue[n]
+		}
+		if doInsert {
+			cols[colidx] = val
+		}
+	}
+
+	if doInsert {
+		t.rows = append(t.rows, &row{cols: cols})
+	}
+	return driver.RowsAffected(1), nil
+}
+
+// hook to simulate broken connections
+var hookQueryBadConn func() bool
+
+func (s *fakeStmt) Query(args []driver.Value) (driver.Rows, error) {
+	if s.closed {
+		return nil, errClosed
+	}
+
+	if hookQueryBadConn != nil && hookQueryBadConn() {
+		return nil, driver.ErrBadConn
+	}
+
+	err := checkSubsetTypes(args)
+	if err != nil {
+		return nil, err
+	}
+
+	db := s.c.db
+	if len(args) != s.placeholders {
+		panic("error in pkg db; should only get here if size is correct")
+	}
+
+	db.mu.Lock()
+	t, ok := db.table(s.table)
+	db.mu.Unlock()
+	if !ok {
+		return nil, fmt.Errorf("fakedb: table %q doesn't exist", s.table)
+	}
+
+	if s.table == "magicquery" {
+		if len(s.whereCol) == 2 && s.whereCol[0] == "op" && s.whereCol[1] == "millis" {
+			if args[0] == "sleep" {
+				time.Sleep(time.Duration(args[1].(int64)) * time.Millisecond)
+			}
+		}
+	}
+
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	colIdx := make(map[string]int) // select column name -> column index in table
+	for _, name := range s.colName {
+		idx := t.columnIndex(name)
+		if idx == -1 {
+			return nil, fmt.Errorf("fakedb: unknown column name %q", name)
+		}
+		colIdx[name] = idx
+	}
+
+	mrows := []*row{}
+rows:
+	for _, trow := range t.rows {
+		// Process the where clause, skipping non-match rows. This is lazy
+		// and just uses fmt.Sprintf("%v") to test equality.  Good enough
+		// for test code.
+		for widx, wcol := range s.whereCol {
+			idx := t.columnIndex(wcol)
+			if idx == -1 {
+				return nil, fmt.Errorf("db: invalid where clause column %q", wcol)
+			}
+			tcol := trow.cols[idx]
+			if bs, ok := tcol.([]byte); ok {
+				// lazy hack to avoid sprintf %v on a []byte
+				tcol = string(bs)
+			}
+			if fmt.Sprintf("%v", tcol) != fmt.Sprintf("%v", args[widx]) {
+				continue rows
+			}
+		}
+		mrow := &row{cols: make([]interface{}, len(s.colName))}
+		for seli, name := range s.colName {
+			mrow.cols[seli] = trow.cols[colIdx[name]]
+		}
+		mrows = append(mrows, mrow)
+	}
+
+	cursor := &rowsCursor{
+		pos:    -1,
+		rows:   mrows,
+		cols:   s.colName,
+		errPos: -1,
+	}
+	return cursor, nil
+}
+
+func (s *fakeStmt) NumInput() int {
+	return s.placeholders
+}
+
+func (tx *fakeTx) Commit() error {
+	tx.c.currTx = nil
+	return nil
+}
+
+func (tx *fakeTx) Rollback() error {
+	tx.c.currTx = nil
+	return nil
+}
+
+type rowsCursor struct {
+	cols   []string
+	pos    int
+	rows   []*row
+	closed bool
+
+	// errPos and err are for making Next return early with error.
+	errPos int
+	err    error
+
+	// a clone of slices to give out to clients, indexed by the
+	// the original slice's first byte address.  we clone them
+	// just so we're able to corrupt them on close.
+	bytesClone map[*byte][]byte
+}
+
+func (rc *rowsCursor) Close() error {
+	if !rc.closed {
+		for _, bs := range rc.bytesClone {
+			bs[0] = 255 // first byte corrupted
+		}
+	}
+	rc.closed = true
+	return nil
+}
+
+func (rc *rowsCursor) Columns() []string {
+	return rc.cols
+}
+
+var rowsCursorNextHook func(dest []driver.Value) error
+
+func (rc *rowsCursor) Next(dest []driver.Value) error {
+	if rowsCursorNextHook != nil {
+		return rowsCursorNextHook(dest)
+	}
+
+	if rc.closed {
+		return errors.New("fakedb: cursor is closed")
+	}
+	rc.pos++
+	if rc.pos == rc.errPos {
+		return rc.err
+	}
+	if rc.pos >= len(rc.rows) {
+		return io.EOF // per interface spec
+	}
+	for i, v := range rc.rows[rc.pos].cols {
+		// TODO(bradfitz): convert to subset types? naah, I
+		// think the subset types should only be input to
+		// driver, but the sql package should be able to handle
+		// a wider range of types coming out of drivers. all
+		// for ease of drivers, and to prevent drivers from
+		// messing up conversions or doing them differently.
+		dest[i] = v
+
+		if bs, ok := v.([]byte); ok {
+			if rc.bytesClone == nil {
+				rc.bytesClone = make(map[*byte][]byte)
+			}
+			clone, ok := rc.bytesClone[&bs[0]]
+			if !ok {
+				clone = make([]byte, len(bs))
+				copy(clone, bs)
+				rc.bytesClone[&bs[0]] = clone
+			}
+			dest[i] = clone
+		}
+	}
+	return nil
+}
+
+// fakeDriverString is like driver.String, but indirects pointers like
+// DefaultValueConverter.
+//
+// This could be surprising behavior to retroactively apply to
+// driver.String now that Go1 is out, but this is convenient for
+// our TestPointerParamsAndScans.
+//
+type fakeDriverString struct{}
+
+func (fakeDriverString) ConvertValue(v interface{}) (driver.Value, error) {
+	switch c := v.(type) {
+	case string, []byte:
+		return v, nil
+	case *string:
+		if c == nil {
+			return nil, nil
+		}
+		return *c, nil
+	}
+	return fmt.Sprintf("%v", v), nil
+}
+
+func converterForType(typ string) driver.ValueConverter {
+	switch typ {
+	case "bool":
+		return driver.Bool
+	case "nullbool":
+		return driver.Null{Converter: driver.Bool}
+	case "int32":
+		return driver.Int32
+	case "string":
+		return driver.NotNull{Converter: fakeDriverString{}}
+	case "nullstring":
+		return driver.Null{Converter: fakeDriverString{}}
+	case "int64":
+		// TODO(coopernurse): add type-specific converter
+		return driver.NotNull{Converter: driver.DefaultParameterConverter}
+	case "nullint64":
+		// TODO(coopernurse): add type-specific converter
+		return driver.Null{Converter: driver.DefaultParameterConverter}
+	case "float64":
+		// TODO(coopernurse): add type-specific converter
+		return driver.NotNull{Converter: driver.DefaultParameterConverter}
+	case "nullfloat64":
+		// TODO(coopernurse): add type-specific converter
+		return driver.Null{Converter: driver.DefaultParameterConverter}
+	case "datetime":
+		return driver.DefaultParameterConverter
+	}
+	panic("invalid fakedb column type of " + typ)
+}
diff --git a/src/database/sql/sql.go b/src/database/sql/sql.go
new file mode 100644
index 000000000..90f813d82
--- /dev/null
+++ b/src/database/sql/sql.go
@@ -0,0 +1,1723 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package sql provides a generic interface around SQL (or SQL-like)
+// databases.
+//
+// The sql package must be used in conjunction with a database driver.
+// See http://golang.org/s/sqldrivers for a list of drivers.
+//
+// For more usage examples, see the wiki page at
+// http://golang.org/s/sqlwiki.
+package sql
+
+import (
+	"database/sql/driver"
+	"errors"
+	"fmt"
+	"io"
+	"runtime"
+	"sync"
+)
+
+var drivers = make(map[string]driver.Driver)
+
+// Register makes a database driver available by the provided name.
+// If Register is called twice with the same name or if driver is nil,
+// it panics.
+func Register(name string, driver driver.Driver) {
+	if driver == nil {
+		panic("sql: Register driver is nil")
+	}
+	if _, dup := drivers[name]; dup {
+		panic("sql: Register called twice for driver " + name)
+	}
+	drivers[name] = driver
+}
+
+// RawBytes is a byte slice that holds a reference to memory owned by
+// the database itself. After a Scan into a RawBytes, the slice is only
+// valid until the next call to Next, Scan, or Close.
+type RawBytes []byte
+
+// NullString represents a string that may be null.
+// NullString implements the Scanner interface so
+// it can be used as a scan destination:
+//
+//  var s NullString
+//  err := db.QueryRow("SELECT name FROM foo WHERE id=?", id).Scan(&s)
+//  ...
+//  if s.Valid {
+//     // use s.String
+//  } else {
+//     // NULL value
+//  }
+//
+type NullString struct {
+	String string
+	Valid  bool // Valid is true if String is not NULL
+}
+
+// Scan implements the Scanner interface.
+func (ns *NullString) Scan(value interface{}) error {
+	if value == nil {
+		ns.String, ns.Valid = "", false
+		return nil
+	}
+	ns.Valid = true
+	return convertAssign(&ns.String, value)
+}
+
+// Value implements the driver Valuer interface.
+func (ns NullString) Value() (driver.Value, error) {
+	if !ns.Valid {
+		return nil, nil
+	}
+	return ns.String, nil
+}
+
+// NullInt64 represents an int64 that may be null.
+// NullInt64 implements the Scanner interface so
+// it can be used as a scan destination, similar to NullString.
+type NullInt64 struct {
+	Int64 int64
+	Valid bool // Valid is true if Int64 is not NULL
+}
+
+// Scan implements the Scanner interface.
+func (n *NullInt64) Scan(value interface{}) error {
+	if value == nil {
+		n.Int64, n.Valid = 0, false
+		return nil
+	}
+	n.Valid = true
+	return convertAssign(&n.Int64, value)
+}
+
+// Value implements the driver Valuer interface.
+func (n NullInt64) Value() (driver.Value, error) {
+	if !n.Valid {
+		return nil, nil
+	}
+	return n.Int64, nil
+}
+
+// NullFloat64 represents a float64 that may be null.
+// NullFloat64 implements the Scanner interface so
+// it can be used as a scan destination, similar to NullString.
+type NullFloat64 struct {
+	Float64 float64
+	Valid   bool // Valid is true if Float64 is not NULL
+}
+
+// Scan implements the Scanner interface.
+func (n *NullFloat64) Scan(value interface{}) error {
+	if value == nil {
+		n.Float64, n.Valid = 0, false
+		return nil
+	}
+	n.Valid = true
+	return convertAssign(&n.Float64, value)
+}
+
+// Value implements the driver Valuer interface.
+func (n NullFloat64) Value() (driver.Value, error) {
+	if !n.Valid {
+		return nil, nil
+	}
+	return n.Float64, nil
+}
+
+// NullBool represents a bool that may be null.
+// NullBool implements the Scanner interface so
+// it can be used as a scan destination, similar to NullString.
+type NullBool struct {
+	Bool  bool
+	Valid bool // Valid is true if Bool is not NULL
+}
+
+// Scan implements the Scanner interface.
+func (n *NullBool) Scan(value interface{}) error {
+	if value == nil {
+		n.Bool, n.Valid = false, false
+		return nil
+	}
+	n.Valid = true
+	return convertAssign(&n.Bool, value)
+}
+
+// Value implements the driver Valuer interface.
+func (n NullBool) Value() (driver.Value, error) {
+	if !n.Valid {
+		return nil, nil
+	}
+	return n.Bool, nil
+}
+
+// Scanner is an interface used by Scan.
+type Scanner interface {
+	// Scan assigns a value from a database driver.
+	//
+	// The src value will be of one of the following restricted
+	// set of types:
+	//
+	//    int64
+	//    float64
+	//    bool
+	//    []byte
+	//    string
+	//    time.Time
+	//    nil - for NULL values
+	//
+	// An error should be returned if the value can not be stored
+	// without loss of information.
+	Scan(src interface{}) error
+}
+
+// ErrNoRows is returned by Scan when QueryRow doesn't return a
+// row. In such a case, QueryRow returns a placeholder *Row value that
+// defers this error until a Scan.
+var ErrNoRows = errors.New("sql: no rows in result set")
+
+// DB is a database handle representing a pool of zero or more
+// underlying connections. It's safe for concurrent use by multiple
+// goroutines.
+//
+// The sql package creates and frees connections automatically; it
+// also maintains a free pool of idle connections. If the database has
+// a concept of per-connection state, such state can only be reliably
+// observed within a transaction. Once DB.Begin is called, the
+// returned Tx is bound to a single connection. Once Commit or
+// Rollback is called on the transaction, that transaction's
+// connection is returned to DB's idle connection pool. The pool size
+// can be controlled with SetMaxIdleConns.
+type DB struct {
+	driver driver.Driver
+	dsn    string
+
+	mu           sync.Mutex // protects following fields
+	freeConn     []*driverConn
+	connRequests []chan connRequest
+	numOpen      int
+	pendingOpens int
+	// Used to signal the need for new connections
+	// a goroutine running connectionOpener() reads on this chan and
+	// maybeOpenNewConnections sends on the chan (one send per needed connection)
+	// It is closed during db.Close(). The close tells the connectionOpener
+	// goroutine to exit.
+	openerCh chan struct{}
+	closed   bool
+	dep      map[finalCloser]depSet
+	lastPut  map[*driverConn]string // stacktrace of last conn's put; debug only
+	maxIdle  int                    // zero means defaultMaxIdleConns; negative means 0
+	maxOpen  int                    // <= 0 means unlimited
+}
+
+// driverConn wraps a driver.Conn with a mutex, to
+// be held during all calls into the Conn. (including any calls onto
+// interfaces returned via that Conn, such as calls on Tx, Stmt,
+// Result, Rows)
+type driverConn struct {
+	db *DB
+
+	sync.Mutex  // guards following
+	ci          driver.Conn
+	closed      bool
+	finalClosed bool // ci.Close has been called
+	openStmt    map[driver.Stmt]bool
+
+	// guarded by db.mu
+	inUse      bool
+	onPut      []func() // code (with db.mu held) run when conn is next returned
+	dbmuClosed bool     // same as closed, but guarded by db.mu, for connIfFree
+}
+
+func (dc *driverConn) releaseConn(err error) {
+	dc.db.putConn(dc, err)
+}
+
+func (dc *driverConn) removeOpenStmt(si driver.Stmt) {
+	dc.Lock()
+	defer dc.Unlock()
+	delete(dc.openStmt, si)
+}
+
+func (dc *driverConn) prepareLocked(query string) (driver.Stmt, error) {
+	si, err := dc.ci.Prepare(query)
+	if err == nil {
+		// Track each driverConn's open statements, so we can close them
+		// before closing the conn.
+		//
+		// TODO(bradfitz): let drivers opt out of caring about
+		// stmt closes if the conn is about to close anyway? For now
+		// do the safe thing, in case stmts need to be closed.
+		//
+		// TODO(bradfitz): after Go 1.2, closing driver.Stmts
+		// should be moved to driverStmt, using unique
+		// *driverStmts everywhere (including from
+		// *Stmt.connStmt, instead of returning a
+		// driver.Stmt), using driverStmt as a pointer
+		// everywhere, and making it a finalCloser.
+		if dc.openStmt == nil {
+			dc.openStmt = make(map[driver.Stmt]bool)
+		}
+		dc.openStmt[si] = true
+	}
+	return si, err
+}
+
+// the dc.db's Mutex is held.
+func (dc *driverConn) closeDBLocked() func() error {
+	dc.Lock()
+	defer dc.Unlock()
+	if dc.closed {
+		return func() error { return errors.New("sql: duplicate driverConn close") }
+	}
+	dc.closed = true
+	return dc.db.removeDepLocked(dc, dc)
+}
+
+func (dc *driverConn) Close() error {
+	dc.Lock()
+	if dc.closed {
+		dc.Unlock()
+		return errors.New("sql: duplicate driverConn close")
+	}
+	dc.closed = true
+	dc.Unlock() // not defer; removeDep finalClose calls may need to lock
+
+	// And now updates that require holding dc.mu.Lock.
+	dc.db.mu.Lock()
+	dc.dbmuClosed = true
+	fn := dc.db.removeDepLocked(dc, dc)
+	dc.db.mu.Unlock()
+	return fn()
+}
+
+func (dc *driverConn) finalClose() error {
+	dc.Lock()
+
+	for si := range dc.openStmt {
+		si.Close()
+	}
+	dc.openStmt = nil
+
+	err := dc.ci.Close()
+	dc.ci = nil
+	dc.finalClosed = true
+	dc.Unlock()
+
+	dc.db.mu.Lock()
+	dc.db.numOpen--
+	dc.db.maybeOpenNewConnections()
+	dc.db.mu.Unlock()
+
+	return err
+}
+
+// driverStmt associates a driver.Stmt with the
+// *driverConn from which it came, so the driverConn's lock can be
+// held during calls.
+type driverStmt struct {
+	sync.Locker // the *driverConn
+	si          driver.Stmt
+}
+
+func (ds *driverStmt) Close() error {
+	ds.Lock()
+	defer ds.Unlock()
+	return ds.si.Close()
+}
+
+// depSet is a finalCloser's outstanding dependencies
+type depSet map[interface{}]bool // set of true bools
+
+// The finalCloser interface is used by (*DB).addDep and related
+// dependency reference counting.
+type finalCloser interface {
+	// finalClose is called when the reference count of an object
+	// goes to zero. (*DB).mu is not held while calling it.
+	finalClose() error
+}
+
+// addDep notes that x now depends on dep, and x's finalClose won't be
+// called until all of x's dependencies are removed with removeDep.
+func (db *DB) addDep(x finalCloser, dep interface{}) {
+	//println(fmt.Sprintf("addDep(%T %p, %T %p)", x, x, dep, dep))
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	db.addDepLocked(x, dep)
+}
+
+func (db *DB) addDepLocked(x finalCloser, dep interface{}) {
+	if db.dep == nil {
+		db.dep = make(map[finalCloser]depSet)
+	}
+	xdep := db.dep[x]
+	if xdep == nil {
+		xdep = make(depSet)
+		db.dep[x] = xdep
+	}
+	xdep[dep] = true
+}
+
+// removeDep notes that x no longer depends on dep.
+// If x still has dependencies, nil is returned.
+// If x no longer has any dependencies, its finalClose method will be
+// called and its error value will be returned.
+func (db *DB) removeDep(x finalCloser, dep interface{}) error {
+	db.mu.Lock()
+	fn := db.removeDepLocked(x, dep)
+	db.mu.Unlock()
+	return fn()
+}
+
+func (db *DB) removeDepLocked(x finalCloser, dep interface{}) func() error {
+	//println(fmt.Sprintf("removeDep(%T %p, %T %p)", x, x, dep, dep))
+
+	xdep, ok := db.dep[x]
+	if !ok {
+		panic(fmt.Sprintf("unpaired removeDep: no deps for %T", x))
+	}
+
+	l0 := len(xdep)
+	delete(xdep, dep)
+
+	switch len(xdep) {
+	case l0:
+		// Nothing removed. Shouldn't happen.
+		panic(fmt.Sprintf("unpaired removeDep: no %T dep on %T", dep, x))
+	case 0:
+		// No more dependencies.
+		delete(db.dep, x)
+		return x.finalClose
+	default:
+		// Dependencies remain.
+		return func() error { return nil }
+	}
+}
+
+// This is the size of the connectionOpener request chan (dn.openerCh).
+// This value should be larger than the maximum typical value
+// used for db.maxOpen. If maxOpen is significantly larger than
+// connectionRequestQueueSize then it is possible for ALL calls into the *DB
+// to block until the connectionOpener can satisfy the backlog of requests.
+var connectionRequestQueueSize = 1000000
+
+// Open opens a database specified by its database driver name and a
+// driver-specific data source name, usually consisting of at least a
+// database name and connection information.
+//
+// Most users will open a database via a driver-specific connection
+// helper function that returns a *DB. No database drivers are included
+// in the Go standard library. See http://golang.org/s/sqldrivers for
+// a list of third-party drivers.
+//
+// Open may just validate its arguments without creating a connection
+// to the database. To verify that the data source name is valid, call
+// Ping.
+//
+// The returned DB is safe for concurrent use by multiple goroutines
+// and maintains its own pool of idle connections. Thus, the Open
+// function should be called just once. It is rarely necessary to
+// close a DB.
+func Open(driverName, dataSourceName string) (*DB, error) {
+	driveri, ok := drivers[driverName]
+	if !ok {
+		return nil, fmt.Errorf("sql: unknown driver %q (forgotten import?)", driverName)
+	}
+	db := &DB{
+		driver:   driveri,
+		dsn:      dataSourceName,
+		openerCh: make(chan struct{}, connectionRequestQueueSize),
+		lastPut:  make(map[*driverConn]string),
+	}
+	go db.connectionOpener()
+	return db, nil
+}
+
+// Ping verifies a connection to the database is still alive,
+// establishing a connection if necessary.
+func (db *DB) Ping() error {
+	// TODO(bradfitz): give drivers an optional hook to implement
+	// this in a more efficient or more reliable way, if they
+	// have one.
+	dc, err := db.conn()
+	if err != nil {
+		return err
+	}
+	db.putConn(dc, nil)
+	return nil
+}
+
+// Close closes the database, releasing any open resources.
+//
+// It is rare to Close a DB, as the DB handle is meant to be
+// long-lived and shared between many goroutines.
+func (db *DB) Close() error {
+	db.mu.Lock()
+	if db.closed { // Make DB.Close idempotent
+		db.mu.Unlock()
+		return nil
+	}
+	close(db.openerCh)
+	var err error
+	fns := make([]func() error, 0, len(db.freeConn))
+	for _, dc := range db.freeConn {
+		fns = append(fns, dc.closeDBLocked())
+	}
+	db.freeConn = nil
+	db.closed = true
+	for _, req := range db.connRequests {
+		close(req)
+	}
+	db.mu.Unlock()
+	for _, fn := range fns {
+		err1 := fn()
+		if err1 != nil {
+			err = err1
+		}
+	}
+	return err
+}
+
+const defaultMaxIdleConns = 2
+
+func (db *DB) maxIdleConnsLocked() int {
+	n := db.maxIdle
+	switch {
+	case n == 0:
+		// TODO(bradfitz): ask driver, if supported, for its default preference
+		return defaultMaxIdleConns
+	case n < 0:
+		return 0
+	default:
+		return n
+	}
+}
+
+// SetMaxIdleConns sets the maximum number of connections in the idle
+// connection pool.
+//
+// If MaxOpenConns is greater than 0 but less than the new MaxIdleConns
+// then the new MaxIdleConns will be reduced to match the MaxOpenConns limit
+//
+// If n <= 0, no idle connections are retained.
+func (db *DB) SetMaxIdleConns(n int) {
+	db.mu.Lock()
+	if n > 0 {
+		db.maxIdle = n
+	} else {
+		// No idle connections.
+		db.maxIdle = -1
+	}
+	// Make sure maxIdle doesn't exceed maxOpen
+	if db.maxOpen > 0 && db.maxIdleConnsLocked() > db.maxOpen {
+		db.maxIdle = db.maxOpen
+	}
+	var closing []*driverConn
+	idleCount := len(db.freeConn)
+	maxIdle := db.maxIdleConnsLocked()
+	if idleCount > maxIdle {
+		closing = db.freeConn[maxIdle:]
+		db.freeConn = db.freeConn[:maxIdle]
+	}
+	db.mu.Unlock()
+	for _, c := range closing {
+		c.Close()
+	}
+}
+
+// SetMaxOpenConns sets the maximum number of open connections to the database.
+//
+// If MaxIdleConns is greater than 0 and the new MaxOpenConns is less than
+// MaxIdleConns, then MaxIdleConns will be reduced to match the new
+// MaxOpenConns limit
+//
+// If n <= 0, then there is no limit on the number of open connections.
+// The default is 0 (unlimited).
+func (db *DB) SetMaxOpenConns(n int) {
+	db.mu.Lock()
+	db.maxOpen = n
+	if n < 0 {
+		db.maxOpen = 0
+	}
+	syncMaxIdle := db.maxOpen > 0 && db.maxIdleConnsLocked() > db.maxOpen
+	db.mu.Unlock()
+	if syncMaxIdle {
+		db.SetMaxIdleConns(n)
+	}
+}
+
+// Assumes db.mu is locked.
+// If there are connRequests and the connection limit hasn't been reached,
+// then tell the connectionOpener to open new connections.
+func (db *DB) maybeOpenNewConnections() {
+	numRequests := len(db.connRequests) - db.pendingOpens
+	if db.maxOpen > 0 {
+		numCanOpen := db.maxOpen - (db.numOpen + db.pendingOpens)
+		if numRequests > numCanOpen {
+			numRequests = numCanOpen
+		}
+	}
+	for numRequests > 0 {
+		db.pendingOpens++
+		numRequests--
+		db.openerCh <- struct{}{}
+	}
+}
+
+// Runs in a separate goroutine, opens new connections when requested.
+func (db *DB) connectionOpener() {
+	for range db.openerCh {
+		db.openNewConnection()
+	}
+}
+
+// Open one new connection
+func (db *DB) openNewConnection() {
+	ci, err := db.driver.Open(db.dsn)
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	if db.closed {
+		if err == nil {
+			ci.Close()
+		}
+		return
+	}
+	db.pendingOpens--
+	if err != nil {
+		db.putConnDBLocked(nil, err)
+		return
+	}
+	dc := &driverConn{
+		db: db,
+		ci: ci,
+	}
+	if db.putConnDBLocked(dc, err) {
+		db.addDepLocked(dc, dc)
+		db.numOpen++
+	} else {
+		ci.Close()
+	}
+}
+
+// connRequest represents one request for a new connection
+// When there are no idle connections available, DB.conn will create
+// a new connRequest and put it on the db.connRequests list.
+type connRequest struct {
+	conn *driverConn
+	err  error
+}
+
+var errDBClosed = errors.New("sql: database is closed")
+
+// conn returns a newly-opened or cached *driverConn
+func (db *DB) conn() (*driverConn, error) {
+	db.mu.Lock()
+	if db.closed {
+		db.mu.Unlock()
+		return nil, errDBClosed
+	}
+
+	// If db.maxOpen > 0 and the number of open connections is over the limit
+	// and there are no free connection, make a request and wait.
+	if db.maxOpen > 0 && db.numOpen >= db.maxOpen && len(db.freeConn) == 0 {
+		// Make the connRequest channel. It's buffered so that the
+		// connectionOpener doesn't block while waiting for the req to be read.
+		req := make(chan connRequest, 1)
+		db.connRequests = append(db.connRequests, req)
+		db.maybeOpenNewConnections()
+		db.mu.Unlock()
+		ret := <-req
+		return ret.conn, ret.err
+	}
+
+	if c := len(db.freeConn); c > 0 {
+		conn := db.freeConn[0]
+		copy(db.freeConn, db.freeConn[1:])
+		db.freeConn = db.freeConn[:c-1]
+		conn.inUse = true
+		db.mu.Unlock()
+		return conn, nil
+	}
+
+	db.numOpen++ // optimistically
+	db.mu.Unlock()
+	ci, err := db.driver.Open(db.dsn)
+	if err != nil {
+		db.mu.Lock()
+		db.numOpen-- // correct for earlier optimism
+		db.mu.Unlock()
+		return nil, err
+	}
+	db.mu.Lock()
+	dc := &driverConn{
+		db: db,
+		ci: ci,
+	}
+	db.addDepLocked(dc, dc)
+	dc.inUse = true
+	db.mu.Unlock()
+	return dc, nil
+}
+
+var (
+	errConnClosed = errors.New("database/sql: internal sentinel error: conn is closed")
+	errConnBusy   = errors.New("database/sql: internal sentinel error: conn is busy")
+)
+
+// connIfFree returns (wanted, nil) if wanted is still a valid conn and
+// isn't in use.
+//
+// The error is errConnClosed if the connection if the requested connection
+// is invalid because it's been closed.
+//
+// The error is errConnBusy if the connection is in use.
+func (db *DB) connIfFree(wanted *driverConn) (*driverConn, error) {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	if wanted.dbmuClosed {
+		return nil, errConnClosed
+	}
+	if wanted.inUse {
+		return nil, errConnBusy
+	}
+	idx := -1
+	for ii, v := range db.freeConn {
+		if v == wanted {
+			idx = ii
+			break
+		}
+	}
+	if idx >= 0 {
+		db.freeConn = append(db.freeConn[:idx], db.freeConn[idx+1:]...)
+		wanted.inUse = true
+		return wanted, nil
+	}
+	// TODO(bradfitz): shouldn't get here. After Go 1.1, change this to:
+	// panic("connIfFree call requested a non-closed, non-busy, non-free conn")
+	// Which passes all the tests, but I'm too paranoid to include this
+	// late in Go 1.1.
+	// Instead, treat it like a busy connection:
+	return nil, errConnBusy
+}
+
+// putConnHook is a hook for testing.
+var putConnHook func(*DB, *driverConn)
+
+// noteUnusedDriverStatement notes that si is no longer used and should
+// be closed whenever possible (when c is next not in use), unless c is
+// already closed.
+func (db *DB) noteUnusedDriverStatement(c *driverConn, si driver.Stmt) {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	if c.inUse {
+		c.onPut = append(c.onPut, func() {
+			si.Close()
+		})
+	} else {
+		c.Lock()
+		defer c.Unlock()
+		if !c.finalClosed {
+			si.Close()
+		}
+	}
+}
+
+// debugGetPut determines whether getConn & putConn calls' stack traces
+// are returned for more verbose crashes.
+const debugGetPut = false
+
+// putConn adds a connection to the db's free pool.
+// err is optionally the last error that occurred on this connection.
+func (db *DB) putConn(dc *driverConn, err error) {
+	db.mu.Lock()
+	if !dc.inUse {
+		if debugGetPut {
+			fmt.Printf("putConn(%v) DUPLICATE was: %s\n\nPREVIOUS was: %s", dc, stack(), db.lastPut[dc])
+		}
+		panic("sql: connection returned that was never out")
+	}
+	if debugGetPut {
+		db.lastPut[dc] = stack()
+	}
+	dc.inUse = false
+
+	for _, fn := range dc.onPut {
+		fn()
+	}
+	dc.onPut = nil
+
+	if err == driver.ErrBadConn {
+		// Don't reuse bad connections.
+		// Since the conn is considered bad and is being discarded, treat it
+		// as closed. Don't decrement the open count here, finalClose will
+		// take care of that.
+		db.maybeOpenNewConnections()
+		db.mu.Unlock()
+		dc.Close()
+		return
+	}
+	if putConnHook != nil {
+		putConnHook(db, dc)
+	}
+	added := db.putConnDBLocked(dc, nil)
+	db.mu.Unlock()
+
+	if !added {
+		dc.Close()
+	}
+}
+
+// Satisfy a connRequest or put the driverConn in the idle pool and return true
+// or return false.
+// putConnDBLocked will satisfy a connRequest if there is one, or it will
+// return the *driverConn to the freeConn list if err == nil and the idle
+// connection limit will not be exceeded.
+// If err != nil, the value of dc is ignored.
+// If err == nil, then dc must not equal nil.
+// If a connRequest was fulfilled or the *driverConn was placed in the
+// freeConn list, then true is returned, otherwise false is returned.
+func (db *DB) putConnDBLocked(dc *driverConn, err error) bool {
+	if c := len(db.connRequests); c > 0 {
+		req := db.connRequests[0]
+		// This copy is O(n) but in practice faster than a linked list.
+		// TODO: consider compacting it down less often and
+		// moving the base instead?
+		copy(db.connRequests, db.connRequests[1:])
+		db.connRequests = db.connRequests[:c-1]
+		if err == nil {
+			dc.inUse = true
+		}
+		req <- connRequest{
+			conn: dc,
+			err:  err,
+		}
+		return true
+	} else if err == nil && !db.closed && db.maxIdleConnsLocked() > len(db.freeConn) {
+		db.freeConn = append(db.freeConn, dc)
+		return true
+	}
+	return false
+}
+
+// maxBadConnRetries is the number of maximum retries if the driver returns
+// driver.ErrBadConn to signal a broken connection.
+const maxBadConnRetries = 10
+
+// Prepare creates a prepared statement for later queries or executions.
+// Multiple queries or executions may be run concurrently from the
+// returned statement.
+func (db *DB) Prepare(query string) (*Stmt, error) {
+	var stmt *Stmt
+	var err error
+	for i := 0; i < maxBadConnRetries; i++ {
+		stmt, err = db.prepare(query)
+		if err != driver.ErrBadConn {
+			break
+		}
+	}
+	return stmt, err
+}
+
+func (db *DB) prepare(query string) (*Stmt, error) {
+	// TODO: check if db.driver supports an optional
+	// driver.Preparer interface and call that instead, if so,
+	// otherwise we make a prepared statement that's bound
+	// to a connection, and to execute this prepared statement
+	// we either need to use this connection (if it's free), else
+	// get a new connection + re-prepare + execute on that one.
+	dc, err := db.conn()
+	if err != nil {
+		return nil, err
+	}
+	dc.Lock()
+	si, err := dc.prepareLocked(query)
+	dc.Unlock()
+	if err != nil {
+		db.putConn(dc, err)
+		return nil, err
+	}
+	stmt := &Stmt{
+		db:    db,
+		query: query,
+		css:   []connStmt{{dc, si}},
+	}
+	db.addDep(stmt, stmt)
+	db.putConn(dc, nil)
+	return stmt, nil
+}
+
+// Exec executes a query without returning any rows.
+// The args are for any placeholder parameters in the query.
+func (db *DB) Exec(query string, args ...interface{}) (Result, error) {
+	var res Result
+	var err error
+	for i := 0; i < maxBadConnRetries; i++ {
+		res, err = db.exec(query, args)
+		if err != driver.ErrBadConn {
+			break
+		}
+	}
+	return res, err
+}
+
+func (db *DB) exec(query string, args []interface{}) (res Result, err error) {
+	dc, err := db.conn()
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		db.putConn(dc, err)
+	}()
+
+	if execer, ok := dc.ci.(driver.Execer); ok {
+		dargs, err := driverArgs(nil, args)
+		if err != nil {
+			return nil, err
+		}
+		dc.Lock()
+		resi, err := execer.Exec(query, dargs)
+		dc.Unlock()
+		if err != driver.ErrSkip {
+			if err != nil {
+				return nil, err
+			}
+			return driverResult{dc, resi}, nil
+		}
+	}
+
+	dc.Lock()
+	si, err := dc.ci.Prepare(query)
+	dc.Unlock()
+	if err != nil {
+		return nil, err
+	}
+	defer withLock(dc, func() { si.Close() })
+	return resultFromStatement(driverStmt{dc, si}, args...)
+}
+
+// Query executes a query that returns rows, typically a SELECT.
+// The args are for any placeholder parameters in the query.
+func (db *DB) Query(query string, args ...interface{}) (*Rows, error) {
+	var rows *Rows
+	var err error
+	for i := 0; i < maxBadConnRetries; i++ {
+		rows, err = db.query(query, args)
+		if err != driver.ErrBadConn {
+			break
+		}
+	}
+	return rows, err
+}
+
+func (db *DB) query(query string, args []interface{}) (*Rows, error) {
+	ci, err := db.conn()
+	if err != nil {
+		return nil, err
+	}
+
+	return db.queryConn(ci, ci.releaseConn, query, args)
+}
+
+// queryConn executes a query on the given connection.
+// The connection gets released by the releaseConn function.
+func (db *DB) queryConn(dc *driverConn, releaseConn func(error), query string, args []interface{}) (*Rows, error) {
+	if queryer, ok := dc.ci.(driver.Queryer); ok {
+		dargs, err := driverArgs(nil, args)
+		if err != nil {
+			releaseConn(err)
+			return nil, err
+		}
+		dc.Lock()
+		rowsi, err := queryer.Query(query, dargs)
+		dc.Unlock()
+		if err != driver.ErrSkip {
+			if err != nil {
+				releaseConn(err)
+				return nil, err
+			}
+			// Note: ownership of dc passes to the *Rows, to be freed
+			// with releaseConn.
+			rows := &Rows{
+				dc:          dc,
+				releaseConn: releaseConn,
+				rowsi:       rowsi,
+			}
+			return rows, nil
+		}
+	}
+
+	dc.Lock()
+	si, err := dc.ci.Prepare(query)
+	dc.Unlock()
+	if err != nil {
+		releaseConn(err)
+		return nil, err
+	}
+
+	ds := driverStmt{dc, si}
+	rowsi, err := rowsiFromStatement(ds, args...)
+	if err != nil {
+		dc.Lock()
+		si.Close()
+		dc.Unlock()
+		releaseConn(err)
+		return nil, err
+	}
+
+	// Note: ownership of ci passes to the *Rows, to be freed
+	// with releaseConn.
+	rows := &Rows{
+		dc:          dc,
+		releaseConn: releaseConn,
+		rowsi:       rowsi,
+		closeStmt:   si,
+	}
+	return rows, nil
+}
+
+// QueryRow executes a query that is expected to return at most one row.
+// QueryRow always return a non-nil value. Errors are deferred until
+// Row's Scan method is called.
+func (db *DB) QueryRow(query string, args ...interface{}) *Row {
+	rows, err := db.Query(query, args...)
+	return &Row{rows: rows, err: err}
+}
+
+// Begin starts a transaction. The isolation level is dependent on
+// the driver.
+func (db *DB) Begin() (*Tx, error) {
+	var tx *Tx
+	var err error
+	for i := 0; i < maxBadConnRetries; i++ {
+		tx, err = db.begin()
+		if err != driver.ErrBadConn {
+			break
+		}
+	}
+	return tx, err
+}
+
+func (db *DB) begin() (tx *Tx, err error) {
+	dc, err := db.conn()
+	if err != nil {
+		return nil, err
+	}
+	dc.Lock()
+	txi, err := dc.ci.Begin()
+	dc.Unlock()
+	if err != nil {
+		db.putConn(dc, err)
+		return nil, err
+	}
+	return &Tx{
+		db:  db,
+		dc:  dc,
+		txi: txi,
+	}, nil
+}
+
+// Driver returns the database's underlying driver.
+func (db *DB) Driver() driver.Driver {
+	return db.driver
+}
+
+// Tx is an in-progress database transaction.
+//
+// A transaction must end with a call to Commit or Rollback.
+//
+// After a call to Commit or Rollback, all operations on the
+// transaction fail with ErrTxDone.
+type Tx struct {
+	db *DB
+
+	// dc is owned exclusively until Commit or Rollback, at which point
+	// it's returned with putConn.
+	dc  *driverConn
+	txi driver.Tx
+
+	// done transitions from false to true exactly once, on Commit
+	// or Rollback. once done, all operations fail with
+	// ErrTxDone.
+	done bool
+}
+
+var ErrTxDone = errors.New("sql: Transaction has already been committed or rolled back")
+
+func (tx *Tx) close() {
+	if tx.done {
+		panic("double close") // internal error
+	}
+	tx.done = true
+	tx.db.putConn(tx.dc, nil)
+	tx.dc = nil
+	tx.txi = nil
+}
+
+func (tx *Tx) grabConn() (*driverConn, error) {
+	if tx.done {
+		return nil, ErrTxDone
+	}
+	return tx.dc, nil
+}
+
+// Commit commits the transaction.
+func (tx *Tx) Commit() error {
+	if tx.done {
+		return ErrTxDone
+	}
+	defer tx.close()
+	tx.dc.Lock()
+	defer tx.dc.Unlock()
+	return tx.txi.Commit()
+}
+
+// Rollback aborts the transaction.
+func (tx *Tx) Rollback() error {
+	if tx.done {
+		return ErrTxDone
+	}
+	defer tx.close()
+	tx.dc.Lock()
+	defer tx.dc.Unlock()
+	return tx.txi.Rollback()
+}
+
+// Prepare creates a prepared statement for use within a transaction.
+//
+// The returned statement operates within the transaction and can no longer
+// be used once the transaction has been committed or rolled back.
+//
+// To use an existing prepared statement on this transaction, see Tx.Stmt.
+func (tx *Tx) Prepare(query string) (*Stmt, error) {
+	// TODO(bradfitz): We could be more efficient here and either
+	// provide a method to take an existing Stmt (created on
+	// perhaps a different Conn), and re-create it on this Conn if
+	// necessary. Or, better: keep a map in DB of query string to
+	// Stmts, and have Stmt.Execute do the right thing and
+	// re-prepare if the Conn in use doesn't have that prepared
+	// statement.  But we'll want to avoid caching the statement
+	// in the case where we only call conn.Prepare implicitly
+	// (such as in db.Exec or tx.Exec), but the caller package
+	// can't be holding a reference to the returned statement.
+	// Perhaps just looking at the reference count (by noting
+	// Stmt.Close) would be enough. We might also want a finalizer
+	// on Stmt to drop the reference count.
+	dc, err := tx.grabConn()
+	if err != nil {
+		return nil, err
+	}
+
+	dc.Lock()
+	si, err := dc.ci.Prepare(query)
+	dc.Unlock()
+	if err != nil {
+		return nil, err
+	}
+
+	stmt := &Stmt{
+		db: tx.db,
+		tx: tx,
+		txsi: &driverStmt{
+			Locker: dc,
+			si:     si,
+		},
+		query: query,
+	}
+	return stmt, nil
+}
+
+// Stmt returns a transaction-specific prepared statement from
+// an existing statement.
+//
+// Example:
+//  updateMoney, err := db.Prepare("UPDATE balance SET money=money+? WHERE id=?")
+//  ...
+//  tx, err := db.Begin()
+//  ...
+//  res, err := tx.Stmt(updateMoney).Exec(123.45, 98293203)
+func (tx *Tx) Stmt(stmt *Stmt) *Stmt {
+	// TODO(bradfitz): optimize this. Currently this re-prepares
+	// each time.  This is fine for now to illustrate the API but
+	// we should really cache already-prepared statements
+	// per-Conn. See also the big comment in Tx.Prepare.
+
+	if tx.db != stmt.db {
+		return &Stmt{stickyErr: errors.New("sql: Tx.Stmt: statement from different database used")}
+	}
+	dc, err := tx.grabConn()
+	if err != nil {
+		return &Stmt{stickyErr: err}
+	}
+	dc.Lock()
+	si, err := dc.ci.Prepare(stmt.query)
+	dc.Unlock()
+	return &Stmt{
+		db: tx.db,
+		tx: tx,
+		txsi: &driverStmt{
+			Locker: dc,
+			si:     si,
+		},
+		query:     stmt.query,
+		stickyErr: err,
+	}
+}
+
+// Exec executes a query that doesn't return rows.
+// For example: an INSERT and UPDATE.
+func (tx *Tx) Exec(query string, args ...interface{}) (Result, error) {
+	dc, err := tx.grabConn()
+	if err != nil {
+		return nil, err
+	}
+
+	if execer, ok := dc.ci.(driver.Execer); ok {
+		dargs, err := driverArgs(nil, args)
+		if err != nil {
+			return nil, err
+		}
+		dc.Lock()
+		resi, err := execer.Exec(query, dargs)
+		dc.Unlock()
+		if err == nil {
+			return driverResult{dc, resi}, nil
+		}
+		if err != driver.ErrSkip {
+			return nil, err
+		}
+	}
+
+	dc.Lock()
+	si, err := dc.ci.Prepare(query)
+	dc.Unlock()
+	if err != nil {
+		return nil, err
+	}
+	defer withLock(dc, func() { si.Close() })
+
+	return resultFromStatement(driverStmt{dc, si}, args...)
+}
+
+// Query executes a query that returns rows, typically a SELECT.
+func (tx *Tx) Query(query string, args ...interface{}) (*Rows, error) {
+	dc, err := tx.grabConn()
+	if err != nil {
+		return nil, err
+	}
+	releaseConn := func(error) {}
+	return tx.db.queryConn(dc, releaseConn, query, args)
+}
+
+// QueryRow executes a query that is expected to return at most one row.
+// QueryRow always return a non-nil value. Errors are deferred until
+// Row's Scan method is called.
+func (tx *Tx) QueryRow(query string, args ...interface{}) *Row {
+	rows, err := tx.Query(query, args...)
+	return &Row{rows: rows, err: err}
+}
+
+// connStmt is a prepared statement on a particular connection.
+type connStmt struct {
+	dc *driverConn
+	si driver.Stmt
+}
+
+// Stmt is a prepared statement. Stmt is safe for concurrent use by multiple goroutines.
+type Stmt struct {
+	// Immutable:
+	db        *DB    // where we came from
+	query     string // that created the Stmt
+	stickyErr error  // if non-nil, this error is returned for all operations
+
+	closemu sync.RWMutex // held exclusively during close, for read otherwise.
+
+	// If in a transaction, else both nil:
+	tx   *Tx
+	txsi *driverStmt
+
+	mu     sync.Mutex // protects the rest of the fields
+	closed bool
+
+	// css is a list of underlying driver statement interfaces
+	// that are valid on particular connections.  This is only
+	// used if tx == nil and one is found that has idle
+	// connections.  If tx != nil, txsi is always used.
+	css []connStmt
+}
+
+// Exec executes a prepared statement with the given arguments and
+// returns a Result summarizing the effect of the statement.
+func (s *Stmt) Exec(args ...interface{}) (Result, error) {
+	s.closemu.RLock()
+	defer s.closemu.RUnlock()
+
+	var res Result
+	for i := 0; i < maxBadConnRetries; i++ {
+		dc, releaseConn, si, err := s.connStmt()
+		if err != nil {
+			if err == driver.ErrBadConn {
+				continue
+			}
+			return nil, err
+		}
+
+		res, err = resultFromStatement(driverStmt{dc, si}, args...)
+		releaseConn(err)
+		if err != driver.ErrBadConn {
+			return res, err
+		}
+	}
+	return nil, driver.ErrBadConn
+}
+
+func resultFromStatement(ds driverStmt, args ...interface{}) (Result, error) {
+	ds.Lock()
+	want := ds.si.NumInput()
+	ds.Unlock()
+
+	// -1 means the driver doesn't know how to count the number of
+	// placeholders, so we won't sanity check input here and instead let the
+	// driver deal with errors.
+	if want != -1 && len(args) != want {
+		return nil, fmt.Errorf("sql: expected %d arguments, got %d", want, len(args))
+	}
+
+	dargs, err := driverArgs(&ds, args)
+	if err != nil {
+		return nil, err
+	}
+
+	ds.Lock()
+	resi, err := ds.si.Exec(dargs)
+	ds.Unlock()
+	if err != nil {
+		return nil, err
+	}
+	return driverResult{ds.Locker, resi}, nil
+}
+
+// connStmt returns a free driver connection on which to execute the
+// statement, a function to call to release the connection, and a
+// statement bound to that connection.
+func (s *Stmt) connStmt() (ci *driverConn, releaseConn func(error), si driver.Stmt, err error) {
+	if err = s.stickyErr; err != nil {
+		return
+	}
+	s.mu.Lock()
+	if s.closed {
+		s.mu.Unlock()
+		err = errors.New("sql: statement is closed")
+		return
+	}
+
+	// In a transaction, we always use the connection that the
+	// transaction was created on.
+	if s.tx != nil {
+		s.mu.Unlock()
+		ci, err = s.tx.grabConn() // blocks, waiting for the connection.
+		if err != nil {
+			return
+		}
+		releaseConn = func(error) {}
+		return ci, releaseConn, s.txsi.si, nil
+	}
+
+	for i := 0; i < len(s.css); i++ {
+		v := s.css[i]
+		_, err := s.db.connIfFree(v.dc)
+		if err == nil {
+			s.mu.Unlock()
+			return v.dc, v.dc.releaseConn, v.si, nil
+		}
+		if err == errConnClosed {
+			// Lazily remove dead conn from our freelist.
+			s.css[i] = s.css[len(s.css)-1]
+			s.css = s.css[:len(s.css)-1]
+			i--
+		}
+
+	}
+	s.mu.Unlock()
+
+	// If all connections are busy, either wait for one to become available (if
+	// we've already hit the maximum number of open connections) or create a
+	// new one.
+	//
+	// TODO(bradfitz): or always wait for one? make configurable later?
+	dc, err := s.db.conn()
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	// Do another pass over the list to see whether this statement has
+	// already been prepared on the connection assigned to us.
+	s.mu.Lock()
+	for _, v := range s.css {
+		if v.dc == dc {
+			s.mu.Unlock()
+			return dc, dc.releaseConn, v.si, nil
+		}
+	}
+	s.mu.Unlock()
+
+	// No luck; we need to prepare the statement on this connection
+	dc.Lock()
+	si, err = dc.prepareLocked(s.query)
+	dc.Unlock()
+	if err != nil {
+		s.db.putConn(dc, err)
+		return nil, nil, nil, err
+	}
+	s.mu.Lock()
+	cs := connStmt{dc, si}
+	s.css = append(s.css, cs)
+	s.mu.Unlock()
+
+	return dc, dc.releaseConn, si, nil
+}
+
+// Query executes a prepared query statement with the given arguments
+// and returns the query results as a *Rows.
+func (s *Stmt) Query(args ...interface{}) (*Rows, error) {
+	s.closemu.RLock()
+	defer s.closemu.RUnlock()
+
+	var rowsi driver.Rows
+	for i := 0; i < maxBadConnRetries; i++ {
+		dc, releaseConn, si, err := s.connStmt()
+		if err != nil {
+			if err == driver.ErrBadConn {
+				continue
+			}
+			return nil, err
+		}
+
+		rowsi, err = rowsiFromStatement(driverStmt{dc, si}, args...)
+		if err == nil {
+			// Note: ownership of ci passes to the *Rows, to be freed
+			// with releaseConn.
+			rows := &Rows{
+				dc:    dc,
+				rowsi: rowsi,
+				// releaseConn set below
+			}
+			s.db.addDep(s, rows)
+			rows.releaseConn = func(err error) {
+				releaseConn(err)
+				s.db.removeDep(s, rows)
+			}
+			return rows, nil
+		}
+
+		releaseConn(err)
+		if err != driver.ErrBadConn {
+			return nil, err
+		}
+	}
+	return nil, driver.ErrBadConn
+}
+
+func rowsiFromStatement(ds driverStmt, args ...interface{}) (driver.Rows, error) {
+	ds.Lock()
+	want := ds.si.NumInput()
+	ds.Unlock()
+
+	// -1 means the driver doesn't know how to count the number of
+	// placeholders, so we won't sanity check input here and instead let the
+	// driver deal with errors.
+	if want != -1 && len(args) != want {
+		return nil, fmt.Errorf("sql: statement expects %d inputs; got %d", want, len(args))
+	}
+
+	dargs, err := driverArgs(&ds, args)
+	if err != nil {
+		return nil, err
+	}
+
+	ds.Lock()
+	rowsi, err := ds.si.Query(dargs)
+	ds.Unlock()
+	if err != nil {
+		return nil, err
+	}
+	return rowsi, nil
+}
+
+// QueryRow executes a prepared query statement with the given arguments.
+// If an error occurs during the execution of the statement, that error will
+// be returned by a call to Scan on the returned *Row, which is always non-nil.
+// If the query selects no rows, the *Row's Scan will return ErrNoRows.
+// Otherwise, the *Row's Scan scans the first selected row and discards
+// the rest.
+//
+// Example usage:
+//
+//  var name string
+//  err := nameByUseridStmt.QueryRow(id).Scan(&name)
+func (s *Stmt) QueryRow(args ...interface{}) *Row {
+	rows, err := s.Query(args...)
+	if err != nil {
+		return &Row{err: err}
+	}
+	return &Row{rows: rows}
+}
+
+// Close closes the statement.
+func (s *Stmt) Close() error {
+	s.closemu.Lock()
+	defer s.closemu.Unlock()
+
+	if s.stickyErr != nil {
+		return s.stickyErr
+	}
+	s.mu.Lock()
+	if s.closed {
+		s.mu.Unlock()
+		return nil
+	}
+	s.closed = true
+
+	if s.tx != nil {
+		s.txsi.Close()
+		s.mu.Unlock()
+		return nil
+	}
+	s.mu.Unlock()
+
+	return s.db.removeDep(s, s)
+}
+
+func (s *Stmt) finalClose() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.css != nil {
+		for _, v := range s.css {
+			s.db.noteUnusedDriverStatement(v.dc, v.si)
+			v.dc.removeOpenStmt(v.si)
+		}
+		s.css = nil
+	}
+	return nil
+}
+
+// Rows is the result of a query. Its cursor starts before the first row
+// of the result set. Use Next to advance through the rows:
+//
+//     rows, err := db.Query("SELECT ...")
+//     ...
+//     defer rows.Close()
+//     for rows.Next() {
+//         var id int
+//         var name string
+//         err = rows.Scan(&id, &name)
+//         ...
+//     }
+//     err = rows.Err() // get any error encountered during iteration
+//     ...
+type Rows struct {
+	dc          *driverConn // owned; must call releaseConn when closed to release
+	releaseConn func(error)
+	rowsi       driver.Rows
+
+	closed    bool
+	lastcols  []driver.Value
+	lasterr   error       // non-nil only if closed is true
+	closeStmt driver.Stmt // if non-nil, statement to Close on close
+}
+
+// Next prepares the next result row for reading with the Scan method.  It
+// returns true on success, or false if there is no next result row or an error
+// happened while preparing it.  Err should be consulted to distinguish between
+// the two cases.
+//
+// Every call to Scan, even the first one, must be preceded by a call to Next.
+func (rs *Rows) Next() bool {
+	if rs.closed {
+		return false
+	}
+	if rs.lastcols == nil {
+		rs.lastcols = make([]driver.Value, len(rs.rowsi.Columns()))
+	}
+	rs.lasterr = rs.rowsi.Next(rs.lastcols)
+	if rs.lasterr != nil {
+		rs.Close()
+		return false
+	}
+	return true
+}
+
+// Err returns the error, if any, that was encountered during iteration.
+// Err may be called after an explicit or implicit Close.
+func (rs *Rows) Err() error {
+	if rs.lasterr == io.EOF {
+		return nil
+	}
+	return rs.lasterr
+}
+
+// Columns returns the column names.
+// Columns returns an error if the rows are closed, or if the rows
+// are from QueryRow and there was a deferred error.
+func (rs *Rows) Columns() ([]string, error) {
+	if rs.closed {
+		return nil, errors.New("sql: Rows are closed")
+	}
+	if rs.rowsi == nil {
+		return nil, errors.New("sql: no Rows available")
+	}
+	return rs.rowsi.Columns(), nil
+}
+
+// Scan copies the columns in the current row into the values pointed
+// at by dest.
+//
+// If an argument has type *[]byte, Scan saves in that argument a copy
+// of the corresponding data. The copy is owned by the caller and can
+// be modified and held indefinitely. The copy can be avoided by using
+// an argument of type *RawBytes instead; see the documentation for
+// RawBytes for restrictions on its use.
+//
+// If an argument has type *interface{}, Scan copies the value
+// provided by the underlying driver without conversion. If the value
+// is of type []byte, a copy is made and the caller owns the result.
+func (rs *Rows) Scan(dest ...interface{}) error {
+	if rs.closed {
+		return errors.New("sql: Rows are closed")
+	}
+	if rs.lastcols == nil {
+		return errors.New("sql: Scan called without calling Next")
+	}
+	if len(dest) != len(rs.lastcols) {
+		return fmt.Errorf("sql: expected %d destination arguments in Scan, not %d", len(rs.lastcols), len(dest))
+	}
+	for i, sv := range rs.lastcols {
+		err := convertAssign(dest[i], sv)
+		if err != nil {
+			return fmt.Errorf("sql: Scan error on column index %d: %v", i, err)
+		}
+	}
+	return nil
+}
+
+var rowsCloseHook func(*Rows, *error)
+
+// Close closes the Rows, preventing further enumeration. If Next returns
+// false, the Rows are closed automatically and it will suffice to check the
+// result of Err. Close is idempotent and does not affect the result of Err.
+func (rs *Rows) Close() error {
+	if rs.closed {
+		return nil
+	}
+	rs.closed = true
+	err := rs.rowsi.Close()
+	if fn := rowsCloseHook; fn != nil {
+		fn(rs, &err)
+	}
+	if rs.closeStmt != nil {
+		rs.closeStmt.Close()
+	}
+	rs.releaseConn(err)
+	return err
+}
+
+// Row is the result of calling QueryRow to select a single row.
+type Row struct {
+	// One of these two will be non-nil:
+	err  error // deferred error for easy chaining
+	rows *Rows
+}
+
+// Scan copies the columns from the matched row into the values
+// pointed at by dest.  If more than one row matches the query,
+// Scan uses the first row and discards the rest.  If no row matches
+// the query, Scan returns ErrNoRows.
+func (r *Row) Scan(dest ...interface{}) error {
+	if r.err != nil {
+		return r.err
+	}
+
+	// TODO(bradfitz): for now we need to defensively clone all
+	// []byte that the driver returned (not permitting
+	// *RawBytes in Rows.Scan), since we're about to close
+	// the Rows in our defer, when we return from this function.
+	// the contract with the driver.Next(...) interface is that it
+	// can return slices into read-only temporary memory that's
+	// only valid until the next Scan/Close.  But the TODO is that
+	// for a lot of drivers, this copy will be unnecessary.  We
+	// should provide an optional interface for drivers to
+	// implement to say, "don't worry, the []bytes that I return
+	// from Next will not be modified again." (for instance, if
+	// they were obtained from the network anyway) But for now we
+	// don't care.
+	defer r.rows.Close()
+	for _, dp := range dest {
+		if _, ok := dp.(*RawBytes); ok {
+			return errors.New("sql: RawBytes isn't allowed on Row.Scan")
+		}
+	}
+
+	if !r.rows.Next() {
+		if err := r.rows.Err(); err != nil {
+			return err
+		}
+		return ErrNoRows
+	}
+	err := r.rows.Scan(dest...)
+	if err != nil {
+		return err
+	}
+	// Make sure the query can be processed to completion with no errors.
+	if err := r.rows.Close(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// A Result summarizes an executed SQL command.
+type Result interface {
+	// LastInsertId returns the integer generated by the database
+	// in response to a command. Typically this will be from an
+	// "auto increment" column when inserting a new row. Not all
+	// databases support this feature, and the syntax of such
+	// statements varies.
+	LastInsertId() (int64, error)
+
+	// RowsAffected returns the number of rows affected by an
+	// update, insert, or delete. Not every database or database
+	// driver may support this.
+	RowsAffected() (int64, error)
+}
+
+type driverResult struct {
+	sync.Locker // the *driverConn
+	resi        driver.Result
+}
+
+func (dr driverResult) LastInsertId() (int64, error) {
+	dr.Lock()
+	defer dr.Unlock()
+	return dr.resi.LastInsertId()
+}
+
+func (dr driverResult) RowsAffected() (int64, error) {
+	dr.Lock()
+	defer dr.Unlock()
+	return dr.resi.RowsAffected()
+}
+
+func stack() string {
+	var buf [2 << 10]byte
+	return string(buf[:runtime.Stack(buf[:], false)])
+}
+
+// withLock runs while holding lk.
+func withLock(lk sync.Locker, fn func()) {
+	lk.Lock()
+	fn()
+	lk.Unlock()
+}
diff --git a/src/database/sql/sql_test.go b/src/database/sql/sql_test.go
new file mode 100644
index 000000000..12e5a6fd6
--- /dev/null
+++ b/src/database/sql/sql_test.go
@@ -0,0 +1,1956 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sql
+
+import (
+	"database/sql/driver"
+	"errors"
+	"fmt"
+	"math/rand"
+	"reflect"
+	"runtime"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+)
+
+func init() {
+	type dbConn struct {
+		db *DB
+		c  *driverConn
+	}
+	freedFrom := make(map[dbConn]string)
+	putConnHook = func(db *DB, c *driverConn) {
+		idx := -1
+		for i, v := range db.freeConn {
+			if v == c {
+				idx = i
+				break
+			}
+		}
+		if idx >= 0 {
+			// print before panic, as panic may get lost due to conflicting panic
+			// (all goroutines asleep) elsewhere, since we might not unlock
+			// the mutex in freeConn here.
+			println("double free of conn. conflicts are:\nA) " + freedFrom[dbConn{db, c}] + "\n\nand\nB) " + stack())
+			panic("double free of conn.")
+		}
+		freedFrom[dbConn{db, c}] = stack()
+	}
+}
+
+const fakeDBName = "foo"
+
+var chrisBirthday = time.Unix(123456789, 0)
+
+func newTestDB(t testing.TB, name string) *DB {
+	db, err := Open("test", fakeDBName)
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	if _, err := db.Exec("WIPE"); err != nil {
+		t.Fatalf("exec wipe: %v", err)
+	}
+	if name == "people" {
+		exec(t, db, "CREATE|people|name=string,age=int32,photo=blob,dead=bool,bdate=datetime")
+		exec(t, db, "INSERT|people|name=Alice,age=?,photo=APHOTO", 1)
+		exec(t, db, "INSERT|people|name=Bob,age=?,photo=BPHOTO", 2)
+		exec(t, db, "INSERT|people|name=Chris,age=?,photo=CPHOTO,bdate=?", 3, chrisBirthday)
+	}
+	if name == "magicquery" {
+		// Magic table name and column, known by fakedb_test.go.
+		exec(t, db, "CREATE|magicquery|op=string,millis=int32")
+		exec(t, db, "INSERT|magicquery|op=sleep,millis=10")
+	}
+	return db
+}
+
+func exec(t testing.TB, db *DB, query string, args ...interface{}) {
+	_, err := db.Exec(query, args...)
+	if err != nil {
+		t.Fatalf("Exec of %q: %v", query, err)
+	}
+}
+
+func closeDB(t testing.TB, db *DB) {
+	if e := recover(); e != nil {
+		fmt.Printf("Panic: %v\n", e)
+		panic(e)
+	}
+	defer setHookpostCloseConn(nil)
+	setHookpostCloseConn(func(_ *fakeConn, err error) {
+		if err != nil {
+			t.Errorf("Error closing fakeConn: %v", err)
+		}
+	})
+	for i, dc := range db.freeConn {
+		if n := len(dc.openStmt); n > 0 {
+			// Just a sanity check. This is legal in
+			// general, but if we make the tests clean up
+			// their statements first, then we can safely
+			// verify this is always zero here, and any
+			// other value is a leak.
+			t.Errorf("while closing db, freeConn %d/%d had %d open stmts; want 0", i, len(db.freeConn), n)
+		}
+	}
+	err := db.Close()
+	if err != nil {
+		t.Fatalf("error closing DB: %v", err)
+	}
+	db.mu.Lock()
+	count := db.numOpen
+	db.mu.Unlock()
+	if count != 0 {
+		t.Fatalf("%d connections still open after closing DB", db.numOpen)
+	}
+}
+
+// numPrepares assumes that db has exactly 1 idle conn and returns
+// its count of calls to Prepare
+func numPrepares(t *testing.T, db *DB) int {
+	if n := len(db.freeConn); n != 1 {
+		t.Fatalf("free conns = %d; want 1", n)
+	}
+	return db.freeConn[0].ci.(*fakeConn).numPrepare
+}
+
+func (db *DB) numDeps() int {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	return len(db.dep)
+}
+
+// Dependencies are closed via a goroutine, so this polls waiting for
+// numDeps to fall to want, waiting up to d.
+func (db *DB) numDepsPollUntil(want int, d time.Duration) int {
+	deadline := time.Now().Add(d)
+	for {
+		n := db.numDeps()
+		if n <= want || time.Now().After(deadline) {
+			return n
+		}
+		time.Sleep(50 * time.Millisecond)
+	}
+}
+
+func (db *DB) numFreeConns() int {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+	return len(db.freeConn)
+}
+
+func (db *DB) dumpDeps(t *testing.T) {
+	for fc := range db.dep {
+		db.dumpDep(t, 0, fc, map[finalCloser]bool{})
+	}
+}
+
+func (db *DB) dumpDep(t *testing.T, depth int, dep finalCloser, seen map[finalCloser]bool) {
+	seen[dep] = true
+	indent := strings.Repeat("  ", depth)
+	ds := db.dep[dep]
+	for k := range ds {
+		t.Logf("%s%T (%p) waiting for -> %T (%p)", indent, dep, dep, k, k)
+		if fc, ok := k.(finalCloser); ok {
+			if !seen[fc] {
+				db.dumpDep(t, depth+1, fc, seen)
+			}
+		}
+	}
+}
+
+func TestQuery(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	prepares0 := numPrepares(t, db)
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	type row struct {
+		age  int
+		name string
+	}
+	got := []row{}
+	for rows.Next() {
+		var r row
+		err = rows.Scan(&r.age, &r.name)
+		if err != nil {
+			t.Fatalf("Scan: %v", err)
+		}
+		got = append(got, r)
+	}
+	err = rows.Err()
+	if err != nil {
+		t.Fatalf("Err: %v", err)
+	}
+	want := []row{
+		{age: 1, name: "Alice"},
+		{age: 2, name: "Bob"},
+		{age: 3, name: "Chris"},
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("mismatch.\n got: %#v\nwant: %#v", got, want)
+	}
+
+	// And verify that the final rows.Next() call, which hit EOF,
+	// also closed the rows connection.
+	if n := db.numFreeConns(); n != 1 {
+		t.Fatalf("free conns after query hitting EOF = %d; want 1", n)
+	}
+	if prepares := numPrepares(t, db) - prepares0; prepares != 1 {
+		t.Errorf("executed %d Prepare statements; want 1", prepares)
+	}
+}
+
+func TestByteOwnership(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	rows, err := db.Query("SELECT|people|name,photo|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	type row struct {
+		name  []byte
+		photo RawBytes
+	}
+	got := []row{}
+	for rows.Next() {
+		var r row
+		err = rows.Scan(&r.name, &r.photo)
+		if err != nil {
+			t.Fatalf("Scan: %v", err)
+		}
+		got = append(got, r)
+	}
+	corruptMemory := []byte("\xffPHOTO")
+	want := []row{
+		{name: []byte("Alice"), photo: corruptMemory},
+		{name: []byte("Bob"), photo: corruptMemory},
+		{name: []byte("Chris"), photo: corruptMemory},
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("mismatch.\n got: %#v\nwant: %#v", got, want)
+	}
+
+	var photo RawBytes
+	err = db.QueryRow("SELECT|people|photo|name=?", "Alice").Scan(&photo)
+	if err == nil {
+		t.Error("want error scanning into RawBytes from QueryRow")
+	}
+}
+
+func TestRowsColumns(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	cols, err := rows.Columns()
+	if err != nil {
+		t.Fatalf("Columns: %v", err)
+	}
+	want := []string{"age", "name"}
+	if !reflect.DeepEqual(cols, want) {
+		t.Errorf("got %#v; want %#v", cols, want)
+	}
+	if err := rows.Close(); err != nil {
+		t.Errorf("error closing rows: %s", err)
+	}
+}
+
+func TestQueryRow(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	var name string
+	var age int
+	var birthday time.Time
+
+	err := db.QueryRow("SELECT|people|age,name|age=?", 3).Scan(&age)
+	if err == nil || !strings.Contains(err.Error(), "expected 2 destination arguments") {
+		t.Errorf("expected error from wrong number of arguments; actually got: %v", err)
+	}
+
+	err = db.QueryRow("SELECT|people|bdate|age=?", 3).Scan(&birthday)
+	if err != nil || !birthday.Equal(chrisBirthday) {
+		t.Errorf("chris birthday = %v, err = %v; want %v", birthday, err, chrisBirthday)
+	}
+
+	err = db.QueryRow("SELECT|people|age,name|age=?", 2).Scan(&age, &name)
+	if err != nil {
+		t.Fatalf("age QueryRow+Scan: %v", err)
+	}
+	if name != "Bob" {
+		t.Errorf("expected name Bob, got %q", name)
+	}
+	if age != 2 {
+		t.Errorf("expected age 2, got %d", age)
+	}
+
+	err = db.QueryRow("SELECT|people|age,name|name=?", "Alice").Scan(&age, &name)
+	if err != nil {
+		t.Fatalf("name QueryRow+Scan: %v", err)
+	}
+	if name != "Alice" {
+		t.Errorf("expected name Alice, got %q", name)
+	}
+	if age != 1 {
+		t.Errorf("expected age 1, got %d", age)
+	}
+
+	var photo []byte
+	err = db.QueryRow("SELECT|people|photo|name=?", "Alice").Scan(&photo)
+	if err != nil {
+		t.Fatalf("photo QueryRow+Scan: %v", err)
+	}
+	want := []byte("APHOTO")
+	if !reflect.DeepEqual(photo, want) {
+		t.Errorf("photo = %q; want %q", photo, want)
+	}
+}
+
+func TestStatementErrorAfterClose(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	stmt, err := db.Prepare("SELECT|people|age|name=?")
+	if err != nil {
+		t.Fatalf("Prepare: %v", err)
+	}
+	err = stmt.Close()
+	if err != nil {
+		t.Fatalf("Close: %v", err)
+	}
+	var name string
+	err = stmt.QueryRow("foo").Scan(&name)
+	if err == nil {
+		t.Errorf("expected error from QueryRow.Scan after Stmt.Close")
+	}
+}
+
+func TestStatementQueryRow(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	stmt, err := db.Prepare("SELECT|people|age|name=?")
+	if err != nil {
+		t.Fatalf("Prepare: %v", err)
+	}
+	defer stmt.Close()
+	var age int
+	for n, tt := range []struct {
+		name string
+		want int
+	}{
+		{"Alice", 1},
+		{"Bob", 2},
+		{"Chris", 3},
+	} {
+		if err := stmt.QueryRow(tt.name).Scan(&age); err != nil {
+			t.Errorf("%d: on %q, QueryRow/Scan: %v", n, tt.name, err)
+		} else if age != tt.want {
+			t.Errorf("%d: age=%d, want %d", n, age, tt.want)
+		}
+	}
+}
+
+// golang.org/issue/3734
+func TestStatementQueryRowConcurrent(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	stmt, err := db.Prepare("SELECT|people|age|name=?")
+	if err != nil {
+		t.Fatalf("Prepare: %v", err)
+	}
+	defer stmt.Close()
+
+	const n = 10
+	ch := make(chan error, n)
+	for i := 0; i < n; i++ {
+		go func() {
+			var age int
+			err := stmt.QueryRow("Alice").Scan(&age)
+			if err == nil && age != 1 {
+				err = fmt.Errorf("unexpected age %d", age)
+			}
+			ch <- err
+		}()
+	}
+	for i := 0; i < n; i++ {
+		if err := <-ch; err != nil {
+			t.Error(err)
+		}
+	}
+}
+
+// just a test of fakedb itself
+func TestBogusPreboundParameters(t *testing.T) {
+	db := newTestDB(t, "foo")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	_, err := db.Prepare("INSERT|t1|name=?,age=bogusconversion")
+	if err == nil {
+		t.Fatalf("expected error")
+	}
+	if err.Error() != `fakedb: invalid conversion to int32 from "bogusconversion"` {
+		t.Errorf("unexpected error: %v", err)
+	}
+}
+
+func TestExec(t *testing.T) {
+	db := newTestDB(t, "foo")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Errorf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+
+	type execTest struct {
+		args    []interface{}
+		wantErr string
+	}
+	execTests := []execTest{
+		// Okay:
+		{[]interface{}{"Brad", 31}, ""},
+		{[]interface{}{"Brad", int64(31)}, ""},
+		{[]interface{}{"Bob", "32"}, ""},
+		{[]interface{}{7, 9}, ""},
+
+		// Invalid conversions:
+		{[]interface{}{"Brad", int64(0xFFFFFFFF)}, "sql: converting argument #1's type: sql/driver: value 4294967295 overflows int32"},
+		{[]interface{}{"Brad", "strconv fail"}, "sql: converting argument #1's type: sql/driver: value \"strconv fail\" can't be converted to int32"},
+
+		// Wrong number of args:
+		{[]interface{}{}, "sql: expected 2 arguments, got 0"},
+		{[]interface{}{1, 2, 3}, "sql: expected 2 arguments, got 3"},
+	}
+	for n, et := range execTests {
+		_, err := stmt.Exec(et.args...)
+		errStr := ""
+		if err != nil {
+			errStr = err.Error()
+		}
+		if errStr != et.wantErr {
+			t.Errorf("stmt.Execute #%d: for %v, got error %q, want error %q",
+				n, et.args, errStr, et.wantErr)
+		}
+	}
+}
+
+func TestTxStmt(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Fatalf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatalf("Begin = %v", err)
+	}
+	txs := tx.Stmt(stmt)
+	defer txs.Close()
+	_, err = txs.Exec("Bobby", 7)
+	if err != nil {
+		t.Fatalf("Exec = %v", err)
+	}
+	err = tx.Commit()
+	if err != nil {
+		t.Fatalf("Commit = %v", err)
+	}
+}
+
+// Issue: http://golang.org/issue/2784
+// This test didn't fail before because we got lucky with the fakedb driver.
+// It was failing, and now not, in github.com/bradfitz/go-sql-test
+func TestTxQuery(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	exec(t, db, "INSERT|t1|name=Alice")
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tx.Rollback()
+
+	r, err := tx.Query("SELECT|t1|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer r.Close()
+
+	if !r.Next() {
+		if r.Err() != nil {
+			t.Fatal(r.Err())
+		}
+		t.Fatal("expected one row")
+	}
+
+	var x string
+	err = r.Scan(&x)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestTxQueryInvalid(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tx.Rollback()
+
+	_, err = tx.Query("SELECT|t1|name|")
+	if err == nil {
+		t.Fatal("Error expected")
+	}
+}
+
+// Tests fix for issue 4433, that retries in Begin happen when
+// conn.Begin() returns ErrBadConn
+func TestTxErrBadConn(t *testing.T) {
+	db, err := Open("test", fakeDBName+";badConn")
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	if _, err := db.Exec("WIPE"); err != nil {
+		t.Fatalf("exec wipe: %v", err)
+	}
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Fatalf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatalf("Begin = %v", err)
+	}
+	txs := tx.Stmt(stmt)
+	defer txs.Close()
+	_, err = txs.Exec("Bobby", 7)
+	if err != nil {
+		t.Fatalf("Exec = %v", err)
+	}
+	err = tx.Commit()
+	if err != nil {
+		t.Fatalf("Commit = %v", err)
+	}
+}
+
+// Tests fix for issue 2542, that we release a lock when querying on
+// a closed connection.
+func TestIssue2542Deadlock(t *testing.T) {
+	db := newTestDB(t, "people")
+	closeDB(t, db)
+	for i := 0; i < 2; i++ {
+		_, err := db.Query("SELECT|people|age,name|")
+		if err == nil {
+			t.Fatalf("expected error")
+		}
+	}
+}
+
+// From golang.org/issue/3865
+func TestCloseStmtBeforeRows(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	s, err := db.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	r, err := s.Query()
+	if err != nil {
+		s.Close()
+		t.Fatal(err)
+	}
+
+	err = s.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	r.Close()
+}
+
+// Tests fix for issue 2788, that we bind nil to a []byte if the
+// value in the column is sql null
+func TestNullByteSlice(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t|id=int32,name=nullstring")
+	exec(t, db, "INSERT|t|id=10,name=?", nil)
+
+	var name []byte
+
+	err := db.QueryRow("SELECT|t|name|id=?", 10).Scan(&name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if name != nil {
+		t.Fatalf("name []byte should be nil for null column value, got: %#v", name)
+	}
+
+	exec(t, db, "INSERT|t|id=11,name=?", "bob")
+	err = db.QueryRow("SELECT|t|name|id=?", 11).Scan(&name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(name) != "bob" {
+		t.Fatalf("name []byte should be bob, got: %q", string(name))
+	}
+}
+
+func TestPointerParamsAndScans(t *testing.T) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t|id=int32,name=nullstring")
+
+	bob := "bob"
+	var name *string
+
+	name = &bob
+	exec(t, db, "INSERT|t|id=10,name=?", name)
+	name = nil
+	exec(t, db, "INSERT|t|id=20,name=?", name)
+
+	err := db.QueryRow("SELECT|t|name|id=?", 10).Scan(&name)
+	if err != nil {
+		t.Fatalf("querying id 10: %v", err)
+	}
+	if name == nil {
+		t.Errorf("id 10's name = nil; want bob")
+	} else if *name != "bob" {
+		t.Errorf("id 10's name = %q; want bob", *name)
+	}
+
+	err = db.QueryRow("SELECT|t|name|id=?", 20).Scan(&name)
+	if err != nil {
+		t.Fatalf("querying id 20: %v", err)
+	}
+	if name != nil {
+		t.Errorf("id 20 = %q; want nil", *name)
+	}
+}
+
+func TestQueryRowClosingStmt(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	var name string
+	var age int
+	err := db.QueryRow("SELECT|people|age,name|age=?", 3).Scan(&age, &name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(db.freeConn) != 1 {
+		t.Fatalf("expected 1 free conn")
+	}
+	fakeConn := db.freeConn[0].ci.(*fakeConn)
+	if made, closed := fakeConn.stmtsMade, fakeConn.stmtsClosed; made != closed {
+		t.Errorf("statement close mismatch: made %d, closed %d", made, closed)
+	}
+}
+
+// Test issue 6651
+func TestIssue6651(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	var v string
+
+	want := "error in rows.Next"
+	rowsCursorNextHook = func(dest []driver.Value) error {
+		return fmt.Errorf(want)
+	}
+	defer func() { rowsCursorNextHook = nil }()
+	err := db.QueryRow("SELECT|people|name|").Scan(&v)
+	if err == nil || err.Error() != want {
+		t.Errorf("error = %q; want %q", err, want)
+	}
+	rowsCursorNextHook = nil
+
+	want = "error in rows.Close"
+	rowsCloseHook = func(rows *Rows, err *error) {
+		*err = fmt.Errorf(want)
+	}
+	defer func() { rowsCloseHook = nil }()
+	err = db.QueryRow("SELECT|people|name|").Scan(&v)
+	if err == nil || err.Error() != want {
+		t.Errorf("error = %q; want %q", err, want)
+	}
+}
+
+type nullTestRow struct {
+	nullParam    interface{}
+	notNullParam interface{}
+	scanNullVal  interface{}
+}
+
+type nullTestSpec struct {
+	nullType    string
+	notNullType string
+	rows        [6]nullTestRow
+}
+
+func TestNullStringParam(t *testing.T) {
+	spec := nullTestSpec{"nullstring", "string", [6]nullTestRow{
+		{NullString{"aqua", true}, "", NullString{"aqua", true}},
+		{NullString{"brown", false}, "", NullString{"", false}},
+		{"chartreuse", "", NullString{"chartreuse", true}},
+		{NullString{"darkred", true}, "", NullString{"darkred", true}},
+		{NullString{"eel", false}, "", NullString{"", false}},
+		{"foo", NullString{"black", false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func TestNullInt64Param(t *testing.T) {
+	spec := nullTestSpec{"nullint64", "int64", [6]nullTestRow{
+		{NullInt64{31, true}, 1, NullInt64{31, true}},
+		{NullInt64{-22, false}, 1, NullInt64{0, false}},
+		{22, 1, NullInt64{22, true}},
+		{NullInt64{33, true}, 1, NullInt64{33, true}},
+		{NullInt64{222, false}, 1, NullInt64{0, false}},
+		{0, NullInt64{31, false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func TestNullFloat64Param(t *testing.T) {
+	spec := nullTestSpec{"nullfloat64", "float64", [6]nullTestRow{
+		{NullFloat64{31.2, true}, 1, NullFloat64{31.2, true}},
+		{NullFloat64{13.1, false}, 1, NullFloat64{0, false}},
+		{-22.9, 1, NullFloat64{-22.9, true}},
+		{NullFloat64{33.81, true}, 1, NullFloat64{33.81, true}},
+		{NullFloat64{222, false}, 1, NullFloat64{0, false}},
+		{10, NullFloat64{31.2, false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func TestNullBoolParam(t *testing.T) {
+	spec := nullTestSpec{"nullbool", "bool", [6]nullTestRow{
+		{NullBool{false, true}, true, NullBool{false, true}},
+		{NullBool{true, false}, false, NullBool{false, false}},
+		{true, true, NullBool{true, true}},
+		{NullBool{true, true}, false, NullBool{true, true}},
+		{NullBool{true, false}, true, NullBool{false, false}},
+		{true, NullBool{true, false}, nil},
+	}}
+	nullTestRun(t, spec)
+}
+
+func nullTestRun(t *testing.T, spec nullTestSpec) {
+	db := newTestDB(t, "")
+	defer closeDB(t, db)
+	exec(t, db, fmt.Sprintf("CREATE|t|id=int32,name=string,nullf=%s,notnullf=%s", spec.nullType, spec.notNullType))
+
+	// Inserts with db.Exec:
+	exec(t, db, "INSERT|t|id=?,name=?,nullf=?,notnullf=?", 1, "alice", spec.rows[0].nullParam, spec.rows[0].notNullParam)
+	exec(t, db, "INSERT|t|id=?,name=?,nullf=?,notnullf=?", 2, "bob", spec.rows[1].nullParam, spec.rows[1].notNullParam)
+
+	// Inserts with a prepared statement:
+	stmt, err := db.Prepare("INSERT|t|id=?,name=?,nullf=?,notnullf=?")
+	if err != nil {
+		t.Fatalf("prepare: %v", err)
+	}
+	defer stmt.Close()
+	if _, err := stmt.Exec(3, "chris", spec.rows[2].nullParam, spec.rows[2].notNullParam); err != nil {
+		t.Errorf("exec insert chris: %v", err)
+	}
+	if _, err := stmt.Exec(4, "dave", spec.rows[3].nullParam, spec.rows[3].notNullParam); err != nil {
+		t.Errorf("exec insert dave: %v", err)
+	}
+	if _, err := stmt.Exec(5, "eleanor", spec.rows[4].nullParam, spec.rows[4].notNullParam); err != nil {
+		t.Errorf("exec insert eleanor: %v", err)
+	}
+
+	// Can't put null val into non-null col
+	if _, err := stmt.Exec(6, "bob", spec.rows[5].nullParam, spec.rows[5].notNullParam); err == nil {
+		t.Errorf("expected error inserting nil val with prepared statement Exec")
+	}
+
+	_, err = db.Exec("INSERT|t|id=?,name=?,nullf=?", 999, nil, nil)
+	if err == nil {
+		// TODO: this test fails, but it's just because
+		// fakeConn implements the optional Execer interface,
+		// so arguably this is the correct behavior.  But
+		// maybe I should flesh out the fakeConn.Exec
+		// implementation so this properly fails.
+		// t.Errorf("expected error inserting nil name with Exec")
+	}
+
+	paramtype := reflect.TypeOf(spec.rows[0].nullParam)
+	bindVal := reflect.New(paramtype).Interface()
+
+	for i := 0; i < 5; i++ {
+		id := i + 1
+		if err := db.QueryRow("SELECT|t|nullf|id=?", id).Scan(bindVal); err != nil {
+			t.Errorf("id=%d Scan: %v", id, err)
+		}
+		bindValDeref := reflect.ValueOf(bindVal).Elem().Interface()
+		if !reflect.DeepEqual(bindValDeref, spec.rows[i].scanNullVal) {
+			t.Errorf("id=%d got %#v, want %#v", id, bindValDeref, spec.rows[i].scanNullVal)
+		}
+	}
+}
+
+// golang.org/issue/4859
+func TestQueryRowNilScanDest(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	var name *string // nil pointer
+	err := db.QueryRow("SELECT|people|name|").Scan(name)
+	want := "sql: Scan error on column index 0: destination pointer is nil"
+	if err == nil || err.Error() != want {
+		t.Errorf("error = %q; want %q", err.Error(), want)
+	}
+}
+
+func TestIssue4902(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	driver := db.driver.(*fakeDriver)
+	opens0 := driver.openCount
+
+	var stmt *Stmt
+	var err error
+	for i := 0; i < 10; i++ {
+		stmt, err = db.Prepare("SELECT|people|name|")
+		if err != nil {
+			t.Fatal(err)
+		}
+		err = stmt.Close()
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	opens := driver.openCount - opens0
+	if opens > 1 {
+		t.Errorf("opens = %d; want <= 1", opens)
+		t.Logf("db = %#v", db)
+		t.Logf("driver = %#v", driver)
+		t.Logf("stmt = %#v", stmt)
+	}
+}
+
+// Issue 3857
+// This used to deadlock.
+func TestSimultaneousQueries(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tx.Rollback()
+
+	r1, err := tx.Query("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer r1.Close()
+
+	r2, err := tx.Query("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer r2.Close()
+}
+
+func TestMaxIdleConns(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	tx.Commit()
+	if got := len(db.freeConn); got != 1 {
+		t.Errorf("freeConns = %d; want 1", got)
+	}
+
+	db.SetMaxIdleConns(0)
+
+	if got := len(db.freeConn); got != 0 {
+		t.Errorf("freeConns after set to zero = %d; want 0", got)
+	}
+
+	tx, err = db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	tx.Commit()
+	if got := len(db.freeConn); got != 0 {
+		t.Errorf("freeConns = %d; want 0", got)
+	}
+}
+
+func TestMaxOpenConns(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+	defer setHookpostCloseConn(nil)
+	setHookpostCloseConn(func(_ *fakeConn, err error) {
+		if err != nil {
+			t.Errorf("Error closing fakeConn: %v", err)
+		}
+	})
+
+	db := newTestDB(t, "magicquery")
+	defer closeDB(t, db)
+
+	driver := db.driver.(*fakeDriver)
+
+	// Force the number of open connections to 0 so we can get an accurate
+	// count for the test
+	db.SetMaxIdleConns(0)
+
+	if g, w := db.numFreeConns(), 0; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPollUntil(0, time.Second); n > 0 {
+		t.Errorf("number of dependencies = %d; expected 0", n)
+		db.dumpDeps(t)
+	}
+
+	driver.mu.Lock()
+	opens0 := driver.openCount
+	closes0 := driver.closeCount
+	driver.mu.Unlock()
+
+	db.SetMaxIdleConns(10)
+	db.SetMaxOpenConns(10)
+
+	stmt, err := db.Prepare("SELECT|magicquery|op|op=?,millis=?")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Start 50 parallel slow queries.
+	const (
+		nquery      = 50
+		sleepMillis = 25
+		nbatch      = 2
+	)
+	var wg sync.WaitGroup
+	for batch := 0; batch < nbatch; batch++ {
+		for i := 0; i < nquery; i++ {
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
+				var op string
+				if err := stmt.QueryRow("sleep", sleepMillis).Scan(&op); err != nil && err != ErrNoRows {
+					t.Error(err)
+				}
+			}()
+		}
+		// Sleep for twice the expected length of time for the
+		// batch of 50 queries above to finish before starting
+		// the next round.
+		time.Sleep(2 * sleepMillis * time.Millisecond)
+	}
+	wg.Wait()
+
+	if g, w := db.numFreeConns(), 10; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPollUntil(20, time.Second); n > 20 {
+		t.Errorf("number of dependencies = %d; expected <= 20", n)
+		db.dumpDeps(t)
+	}
+
+	driver.mu.Lock()
+	opens := driver.openCount - opens0
+	closes := driver.closeCount - closes0
+	driver.mu.Unlock()
+
+	if opens > 10 {
+		t.Logf("open calls = %d", opens)
+		t.Logf("close calls = %d", closes)
+		t.Errorf("db connections opened = %d; want <= 10", opens)
+		db.dumpDeps(t)
+	}
+
+	if err := stmt.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	if g, w := db.numFreeConns(), 10; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPollUntil(10, time.Second); n > 10 {
+		t.Errorf("number of dependencies = %d; expected <= 10", n)
+		db.dumpDeps(t)
+	}
+
+	db.SetMaxOpenConns(5)
+
+	if g, w := db.numFreeConns(), 5; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPollUntil(5, time.Second); n > 5 {
+		t.Errorf("number of dependencies = %d; expected 0", n)
+		db.dumpDeps(t)
+	}
+
+	db.SetMaxOpenConns(0)
+
+	if g, w := db.numFreeConns(), 5; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPollUntil(5, time.Second); n > 5 {
+		t.Errorf("number of dependencies = %d; expected 0", n)
+		db.dumpDeps(t)
+	}
+
+	db.SetMaxIdleConns(0)
+
+	if g, w := db.numFreeConns(), 0; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPollUntil(0, time.Second); n > 0 {
+		t.Errorf("number of dependencies = %d; expected 0", n)
+		db.dumpDeps(t)
+	}
+}
+
+func TestSingleOpenConn(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxOpenConns(1)
+
+	rows, err := db.Query("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = rows.Close(); err != nil {
+		t.Fatal(err)
+	}
+	// shouldn't deadlock
+	rows, err = db.Query("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = rows.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+// golang.org/issue/5323
+func TestStmtCloseDeps(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+	defer setHookpostCloseConn(nil)
+	setHookpostCloseConn(func(_ *fakeConn, err error) {
+		if err != nil {
+			t.Errorf("Error closing fakeConn: %v", err)
+		}
+	})
+
+	db := newTestDB(t, "magicquery")
+	defer closeDB(t, db)
+
+	driver := db.driver.(*fakeDriver)
+
+	driver.mu.Lock()
+	opens0 := driver.openCount
+	closes0 := driver.closeCount
+	driver.mu.Unlock()
+	openDelta0 := opens0 - closes0
+
+	stmt, err := db.Prepare("SELECT|magicquery|op|op=?,millis=?")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Start 50 parallel slow queries.
+	const (
+		nquery      = 50
+		sleepMillis = 25
+		nbatch      = 2
+	)
+	var wg sync.WaitGroup
+	for batch := 0; batch < nbatch; batch++ {
+		for i := 0; i < nquery; i++ {
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
+				var op string
+				if err := stmt.QueryRow("sleep", sleepMillis).Scan(&op); err != nil && err != ErrNoRows {
+					t.Error(err)
+				}
+			}()
+		}
+		// Sleep for twice the expected length of time for the
+		// batch of 50 queries above to finish before starting
+		// the next round.
+		time.Sleep(2 * sleepMillis * time.Millisecond)
+	}
+	wg.Wait()
+
+	if g, w := db.numFreeConns(), 2; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPollUntil(4, time.Second); n > 4 {
+		t.Errorf("number of dependencies = %d; expected <= 4", n)
+		db.dumpDeps(t)
+	}
+
+	driver.mu.Lock()
+	opens := driver.openCount - opens0
+	closes := driver.closeCount - closes0
+	openDelta := (driver.openCount - driver.closeCount) - openDelta0
+	driver.mu.Unlock()
+
+	if openDelta > 2 {
+		t.Logf("open calls = %d", opens)
+		t.Logf("close calls = %d", closes)
+		t.Logf("open delta = %d", openDelta)
+		t.Errorf("db connections opened = %d; want <= 2", openDelta)
+		db.dumpDeps(t)
+	}
+
+	if len(stmt.css) > nquery {
+		t.Errorf("len(stmt.css) = %d; want <= %d", len(stmt.css), nquery)
+	}
+
+	if err := stmt.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	if g, w := db.numFreeConns(), 2; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPollUntil(2, time.Second); n > 2 {
+		t.Errorf("number of dependencies = %d; expected <= 2", n)
+		db.dumpDeps(t)
+	}
+
+	db.SetMaxIdleConns(0)
+
+	if g, w := db.numFreeConns(), 0; g != w {
+		t.Errorf("free conns = %d; want %d", g, w)
+	}
+
+	if n := db.numDepsPollUntil(0, time.Second); n > 0 {
+		t.Errorf("number of dependencies = %d; expected 0", n)
+		db.dumpDeps(t)
+	}
+}
+
+// golang.org/issue/5046
+func TestCloseConnBeforeStmts(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	defer setHookpostCloseConn(nil)
+	setHookpostCloseConn(func(_ *fakeConn, err error) {
+		if err != nil {
+			t.Errorf("Error closing fakeConn: %v; from %s", err, stack())
+			db.dumpDeps(t)
+			t.Errorf("DB = %#v", db)
+		}
+	})
+
+	stmt, err := db.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(db.freeConn) != 1 {
+		t.Fatalf("expected 1 freeConn; got %d", len(db.freeConn))
+	}
+	dc := db.freeConn[0]
+	if dc.closed {
+		t.Errorf("conn shouldn't be closed")
+	}
+
+	if n := len(dc.openStmt); n != 1 {
+		t.Errorf("driverConn num openStmt = %d; want 1", n)
+	}
+	err = db.Close()
+	if err != nil {
+		t.Errorf("db Close = %v", err)
+	}
+	if !dc.closed {
+		t.Errorf("after db.Close, driverConn should be closed")
+	}
+	if n := len(dc.openStmt); n != 0 {
+		t.Errorf("driverConn num openStmt = %d; want 0", n)
+	}
+
+	err = stmt.Close()
+	if err != nil {
+		t.Errorf("Stmt close = %v", err)
+	}
+
+	if !dc.closed {
+		t.Errorf("conn should be closed")
+	}
+	if dc.ci != nil {
+		t.Errorf("after Stmt Close, driverConn's Conn interface should be nil")
+	}
+}
+
+// golang.org/issue/5283: don't release the Rows' connection in Close
+// before calling Stmt.Close.
+func TestRowsCloseOrder(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxIdleConns(0)
+	setStrictFakeConnClose(t)
+	defer setStrictFakeConnClose(nil)
+
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = rows.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestRowsImplicitClose(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	want, fail := 2, errors.New("fail")
+	r := rows.rowsi.(*rowsCursor)
+	r.errPos, r.err = want, fail
+
+	got := 0
+	for rows.Next() {
+		got++
+	}
+	if got != want {
+		t.Errorf("got %d rows, want %d", got, want)
+	}
+	if err := rows.Err(); err != fail {
+		t.Errorf("got error %v, want %v", err, fail)
+	}
+	if !r.closed {
+		t.Errorf("r.closed is false, want true")
+	}
+}
+
+func TestStmtCloseOrder(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxIdleConns(0)
+	setStrictFakeConnClose(t)
+	defer setStrictFakeConnClose(nil)
+
+	_, err := db.Query("SELECT|non_existent|name|")
+	if err == nil {
+		t.Fatal("Quering non-existent table should fail")
+	}
+}
+
+// golang.org/issue/5781
+func TestErrBadConnReconnect(t *testing.T) {
+	db := newTestDB(t, "foo")
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+
+	simulateBadConn := func(name string, hook *func() bool, op func() error) {
+		broken, retried := false, false
+		numOpen := db.numOpen
+
+		// simulate a broken connection on the first try
+		*hook = func() bool {
+			if !broken {
+				broken = true
+				return true
+			}
+			retried = true
+			return false
+		}
+
+		if err := op(); err != nil {
+			t.Errorf(name+": %v", err)
+			return
+		}
+
+		if !broken || !retried {
+			t.Error(name + ": Failed to simulate broken connection")
+		}
+		*hook = nil
+
+		if numOpen != db.numOpen {
+			t.Errorf(name+": leaked %d connection(s)!", db.numOpen-numOpen)
+			numOpen = db.numOpen
+		}
+	}
+
+	// db.Exec
+	dbExec := func() error {
+		_, err := db.Exec("INSERT|t1|name=?,age=?,dead=?", "Gordon", 3, true)
+		return err
+	}
+	simulateBadConn("db.Exec prepare", &hookPrepareBadConn, dbExec)
+	simulateBadConn("db.Exec exec", &hookExecBadConn, dbExec)
+
+	// db.Query
+	dbQuery := func() error {
+		rows, err := db.Query("SELECT|t1|age,name|")
+		if err == nil {
+			err = rows.Close()
+		}
+		return err
+	}
+	simulateBadConn("db.Query prepare", &hookPrepareBadConn, dbQuery)
+	simulateBadConn("db.Query query", &hookQueryBadConn, dbQuery)
+
+	// db.Prepare
+	simulateBadConn("db.Prepare", &hookPrepareBadConn, func() error {
+		stmt, err := db.Prepare("INSERT|t1|name=?,age=?,dead=?")
+		if err != nil {
+			return err
+		}
+		stmt.Close()
+		return nil
+	})
+
+	// Provide a way to force a re-prepare of a statement on next execution
+	forcePrepare := func(stmt *Stmt) {
+		stmt.css = nil
+	}
+
+	// stmt.Exec
+	stmt1, err := db.Prepare("INSERT|t1|name=?,age=?,dead=?")
+	if err != nil {
+		t.Fatalf("prepare: %v", err)
+	}
+	defer stmt1.Close()
+	// make sure we must prepare the stmt first
+	forcePrepare(stmt1)
+
+	stmtExec := func() error {
+		_, err := stmt1.Exec("Gopher", 3, false)
+		return err
+	}
+	simulateBadConn("stmt.Exec prepare", &hookPrepareBadConn, stmtExec)
+	simulateBadConn("stmt.Exec exec", &hookExecBadConn, stmtExec)
+
+	// stmt.Query
+	stmt2, err := db.Prepare("SELECT|t1|age,name|")
+	if err != nil {
+		t.Fatalf("prepare: %v", err)
+	}
+	defer stmt2.Close()
+	// make sure we must prepare the stmt first
+	forcePrepare(stmt2)
+
+	stmtQuery := func() error {
+		rows, err := stmt2.Query()
+		if err == nil {
+			err = rows.Close()
+		}
+		return err
+	}
+	simulateBadConn("stmt.Query prepare", &hookPrepareBadConn, stmtQuery)
+	simulateBadConn("stmt.Query exec", &hookQueryBadConn, stmtQuery)
+}
+
+type concurrentTest interface {
+	init(t testing.TB, db *DB)
+	finish(t testing.TB)
+	test(t testing.TB) error
+}
+
+type concurrentDBQueryTest struct {
+	db *DB
+}
+
+func (c *concurrentDBQueryTest) init(t testing.TB, db *DB) {
+	c.db = db
+}
+
+func (c *concurrentDBQueryTest) finish(t testing.TB) {
+	c.db = nil
+}
+
+func (c *concurrentDBQueryTest) test(t testing.TB) error {
+	rows, err := c.db.Query("SELECT|people|name|")
+	if err != nil {
+		t.Error(err)
+		return err
+	}
+	var name string
+	for rows.Next() {
+		rows.Scan(&name)
+	}
+	rows.Close()
+	return nil
+}
+
+type concurrentDBExecTest struct {
+	db *DB
+}
+
+func (c *concurrentDBExecTest) init(t testing.TB, db *DB) {
+	c.db = db
+}
+
+func (c *concurrentDBExecTest) finish(t testing.TB) {
+	c.db = nil
+}
+
+func (c *concurrentDBExecTest) test(t testing.TB) error {
+	_, err := c.db.Exec("NOSERT|people|name=Chris,age=?,photo=CPHOTO,bdate=?", 3, chrisBirthday)
+	if err != nil {
+		t.Error(err)
+		return err
+	}
+	return nil
+}
+
+type concurrentStmtQueryTest struct {
+	db   *DB
+	stmt *Stmt
+}
+
+func (c *concurrentStmtQueryTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.stmt, err = db.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentStmtQueryTest) finish(t testing.TB) {
+	if c.stmt != nil {
+		c.stmt.Close()
+		c.stmt = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentStmtQueryTest) test(t testing.TB) error {
+	rows, err := c.stmt.Query()
+	if err != nil {
+		t.Errorf("error on query:  %v", err)
+		return err
+	}
+
+	var name string
+	for rows.Next() {
+		rows.Scan(&name)
+	}
+	rows.Close()
+	return nil
+}
+
+type concurrentStmtExecTest struct {
+	db   *DB
+	stmt *Stmt
+}
+
+func (c *concurrentStmtExecTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.stmt, err = db.Prepare("NOSERT|people|name=Chris,age=?,photo=CPHOTO,bdate=?")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentStmtExecTest) finish(t testing.TB) {
+	if c.stmt != nil {
+		c.stmt.Close()
+		c.stmt = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentStmtExecTest) test(t testing.TB) error {
+	_, err := c.stmt.Exec(3, chrisBirthday)
+	if err != nil {
+		t.Errorf("error on exec:  %v", err)
+		return err
+	}
+	return nil
+}
+
+type concurrentTxQueryTest struct {
+	db *DB
+	tx *Tx
+}
+
+func (c *concurrentTxQueryTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.tx, err = c.db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentTxQueryTest) finish(t testing.TB) {
+	if c.tx != nil {
+		c.tx.Rollback()
+		c.tx = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentTxQueryTest) test(t testing.TB) error {
+	rows, err := c.db.Query("SELECT|people|name|")
+	if err != nil {
+		t.Error(err)
+		return err
+	}
+	var name string
+	for rows.Next() {
+		rows.Scan(&name)
+	}
+	rows.Close()
+	return nil
+}
+
+type concurrentTxExecTest struct {
+	db *DB
+	tx *Tx
+}
+
+func (c *concurrentTxExecTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.tx, err = c.db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentTxExecTest) finish(t testing.TB) {
+	if c.tx != nil {
+		c.tx.Rollback()
+		c.tx = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentTxExecTest) test(t testing.TB) error {
+	_, err := c.tx.Exec("NOSERT|people|name=Chris,age=?,photo=CPHOTO,bdate=?", 3, chrisBirthday)
+	if err != nil {
+		t.Error(err)
+		return err
+	}
+	return nil
+}
+
+type concurrentTxStmtQueryTest struct {
+	db   *DB
+	tx   *Tx
+	stmt *Stmt
+}
+
+func (c *concurrentTxStmtQueryTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.tx, err = c.db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.stmt, err = c.tx.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentTxStmtQueryTest) finish(t testing.TB) {
+	if c.stmt != nil {
+		c.stmt.Close()
+		c.stmt = nil
+	}
+	if c.tx != nil {
+		c.tx.Rollback()
+		c.tx = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentTxStmtQueryTest) test(t testing.TB) error {
+	rows, err := c.stmt.Query()
+	if err != nil {
+		t.Errorf("error on query:  %v", err)
+		return err
+	}
+
+	var name string
+	for rows.Next() {
+		rows.Scan(&name)
+	}
+	rows.Close()
+	return nil
+}
+
+type concurrentTxStmtExecTest struct {
+	db   *DB
+	tx   *Tx
+	stmt *Stmt
+}
+
+func (c *concurrentTxStmtExecTest) init(t testing.TB, db *DB) {
+	c.db = db
+	var err error
+	c.tx, err = c.db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.stmt, err = c.tx.Prepare("NOSERT|people|name=Chris,age=?,photo=CPHOTO,bdate=?")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func (c *concurrentTxStmtExecTest) finish(t testing.TB) {
+	if c.stmt != nil {
+		c.stmt.Close()
+		c.stmt = nil
+	}
+	if c.tx != nil {
+		c.tx.Rollback()
+		c.tx = nil
+	}
+	c.db = nil
+}
+
+func (c *concurrentTxStmtExecTest) test(t testing.TB) error {
+	_, err := c.stmt.Exec(3, chrisBirthday)
+	if err != nil {
+		t.Errorf("error on exec:  %v", err)
+		return err
+	}
+	return nil
+}
+
+type concurrentRandomTest struct {
+	tests []concurrentTest
+}
+
+func (c *concurrentRandomTest) init(t testing.TB, db *DB) {
+	c.tests = []concurrentTest{
+		new(concurrentDBQueryTest),
+		new(concurrentDBExecTest),
+		new(concurrentStmtQueryTest),
+		new(concurrentStmtExecTest),
+		new(concurrentTxQueryTest),
+		new(concurrentTxExecTest),
+		new(concurrentTxStmtQueryTest),
+		new(concurrentTxStmtExecTest),
+	}
+	for _, ct := range c.tests {
+		ct.init(t, db)
+	}
+}
+
+func (c *concurrentRandomTest) finish(t testing.TB) {
+	for _, ct := range c.tests {
+		ct.finish(t)
+	}
+}
+
+func (c *concurrentRandomTest) test(t testing.TB) error {
+	ct := c.tests[rand.Intn(len(c.tests))]
+	return ct.test(t)
+}
+
+func doConcurrentTest(t testing.TB, ct concurrentTest) {
+	maxProcs, numReqs := 1, 500
+	if testing.Short() {
+		maxProcs, numReqs = 4, 50
+	}
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(maxProcs))
+
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	ct.init(t, db)
+	defer ct.finish(t)
+
+	var wg sync.WaitGroup
+	wg.Add(numReqs)
+
+	reqs := make(chan bool)
+	defer close(reqs)
+
+	for i := 0; i < maxProcs*2; i++ {
+		go func() {
+			for range reqs {
+				err := ct.test(t)
+				if err != nil {
+					wg.Done()
+					continue
+				}
+				wg.Done()
+			}
+		}()
+	}
+
+	for i := 0; i < numReqs; i++ {
+		reqs <- true
+	}
+
+	wg.Wait()
+}
+
+func manyConcurrentQueries(t testing.TB) {
+	maxProcs, numReqs := 16, 500
+	if testing.Short() {
+		maxProcs, numReqs = 4, 50
+	}
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(maxProcs))
+
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	stmt, err := db.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stmt.Close()
+
+	var wg sync.WaitGroup
+	wg.Add(numReqs)
+
+	reqs := make(chan bool)
+	defer close(reqs)
+
+	for i := 0; i < maxProcs*2; i++ {
+		go func() {
+			for range reqs {
+				rows, err := stmt.Query()
+				if err != nil {
+					t.Errorf("error on query:  %v", err)
+					wg.Done()
+					continue
+				}
+
+				var name string
+				for rows.Next() {
+					rows.Scan(&name)
+				}
+				rows.Close()
+
+				wg.Done()
+			}
+		}()
+	}
+
+	for i := 0; i < numReqs; i++ {
+		reqs <- true
+	}
+
+	wg.Wait()
+}
+
+func TestIssue6081(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	drv := db.driver.(*fakeDriver)
+	drv.mu.Lock()
+	opens0 := drv.openCount
+	closes0 := drv.closeCount
+	drv.mu.Unlock()
+
+	stmt, err := db.Prepare("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	rowsCloseHook = func(rows *Rows, err *error) {
+		*err = driver.ErrBadConn
+	}
+	defer func() { rowsCloseHook = nil }()
+	for i := 0; i < 10; i++ {
+		rows, err := stmt.Query()
+		if err != nil {
+			t.Fatal(err)
+		}
+		rows.Close()
+	}
+	if n := len(stmt.css); n > 1 {
+		t.Errorf("len(css slice) = %d; want <= 1", n)
+	}
+	stmt.Close()
+	if n := len(stmt.css); n != 0 {
+		t.Errorf("len(css slice) after Close = %d; want 0", n)
+	}
+
+	drv.mu.Lock()
+	opens := drv.openCount - opens0
+	closes := drv.closeCount - closes0
+	drv.mu.Unlock()
+	if opens < 9 {
+		t.Errorf("opens = %d; want >= 9", opens)
+	}
+	if closes < 9 {
+		t.Errorf("closes = %d; want >= 9", closes)
+	}
+}
+
+func TestConcurrency(t *testing.T) {
+	doConcurrentTest(t, new(concurrentDBQueryTest))
+	doConcurrentTest(t, new(concurrentDBExecTest))
+	doConcurrentTest(t, new(concurrentStmtQueryTest))
+	doConcurrentTest(t, new(concurrentStmtExecTest))
+	doConcurrentTest(t, new(concurrentTxQueryTest))
+	doConcurrentTest(t, new(concurrentTxExecTest))
+	doConcurrentTest(t, new(concurrentTxStmtQueryTest))
+	doConcurrentTest(t, new(concurrentTxStmtExecTest))
+	doConcurrentTest(t, new(concurrentRandomTest))
+}
+
+func TestConnectionLeak(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	// Start by opening defaultMaxIdleConns
+	rows := make([]*Rows, defaultMaxIdleConns)
+	// We need to SetMaxOpenConns > MaxIdleConns, so the DB can open
+	// a new connection and we can fill the idle queue with the released
+	// connections.
+	db.SetMaxOpenConns(len(rows) + 1)
+	for ii := range rows {
+		r, err := db.Query("SELECT|people|name|")
+		if err != nil {
+			t.Fatal(err)
+		}
+		r.Next()
+		if err := r.Err(); err != nil {
+			t.Fatal(err)
+		}
+		rows[ii] = r
+	}
+	// Now we have defaultMaxIdleConns busy connections. Open
+	// a new one, but wait until the busy connections are released
+	// before returning control to DB.
+	drv := db.driver.(*fakeDriver)
+	drv.waitCh = make(chan struct{}, 1)
+	drv.waitingCh = make(chan struct{}, 1)
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		r, err := db.Query("SELECT|people|name|")
+		if err != nil {
+			t.Fatal(err)
+		}
+		r.Close()
+		wg.Done()
+	}()
+	// Wait until the goroutine we've just created has started waiting.
+	<-drv.waitingCh
+	// Now close the busy connections. This provides a connection for
+	// the blocked goroutine and then fills up the idle queue.
+	for _, v := range rows {
+		v.Close()
+	}
+	// At this point we give the new connection to DB. This connection is
+	// now useless, since the idle queue is full and there are no pending
+	// requests. DB should deal with this situation without leaking the
+	// connection.
+	drv.waitCh <- struct{}{}
+	wg.Wait()
+}
+
+func BenchmarkConcurrentDBExec(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentDBExecTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentStmtQuery(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentStmtQueryTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentStmtExec(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentStmtExecTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentTxQuery(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentTxQueryTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentTxExec(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentTxExecTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentTxStmtQuery(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentTxStmtQueryTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentTxStmtExec(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentTxStmtExecTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}
+
+func BenchmarkConcurrentRandom(b *testing.B) {
+	b.ReportAllocs()
+	ct := new(concurrentRandomTest)
+	for i := 0; i < b.N; i++ {
+		doConcurrentTest(b, ct)
+	}
+}