Bug#20836 Selecting into variables results in wrong results being returned

This error is displayed anytime the SELECT statement needs a temp table to
return correct results because the object (select_dumpvar) that represents
variables named in the INTO clause stored the results before the temp
table was considered.  The problem was fixed by creating the necessary
Item_func_set_user_var objects once the correct data is ready.


mysql-test/r/distinct.result:
  Bug#20836 Selecting into variables results in wrong results being returned
  - Added results
mysql-test/t/distinct.test:
  Bug#20836 Selecting into variables results in wrong results being returned
  - Added various Selects that use the INTO statement and a temp table.
  - Added Select Into Outfile variant tests also.
sql/sql_class.cc:
  Bug#20836 Selecting into variables results in wrong results being returned
  - The select_dumpvar variable created a Item_func_set_user_var too early
  and once set, it was not possible to change.  The Item_func_set_user_var
  is now created once the final results are available.
sql/sql_class.h:
  Bug#20836 Selecting into variables results in wrong results being returned
  - Removed unnecessary object members.

1 files changed, 65 insertions, 0 deletions

diff --git a/mysql-test/t/distinct.test b/mysql-test/t/distinct.test
index 2a87427a2b6..a057eee8e37 100644
--- a/mysql-test/t/distinct.test
+++ b/mysql-test/t/distinct.test
@@ -389,4 +389,69 @@ explain SELECT DISTINCT a, b FROM t1 ORDER BY b;
 SELECT DISTINCT a, b FROM t1 ORDER BY b;
 DROP TABLE t1;
 
+#
+#Bug #20836: Selecting into variables results in wrong results being returned
+#
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+
+CREATE TABLE t1 (id INT NOT NULL, fruit_id INT NOT NULL, fruit_name varchar(20)
+default NULL);
+
+INSERT INTO t1 VALUES (1,1,'ORANGE');
+INSERT INTO t1 VALUES (2,2,'APPLE');
+INSERT INTO t1 VALUES (3,2,'APPLE');
+INSERT INTO t1 VALUES (4,3,'PEAR');
+
+SELECT DISTINCT fruit_id, fruit_name INTO @v1, @v2 FROM t1 WHERE fruit_name = 
+'APPLE';
+SELECT @v1, @v2;
+
+SELECT DISTINCT fruit_id, fruit_name INTO @v3, @v4 FROM t1 GROUP BY fruit_id, 
+fruit_name HAVING fruit_name = 'APPLE';
+SELECT @v3, @v4;
+
+SELECT DISTINCT @v5:= fruit_id, @v6:= fruit_name INTO @v7, @v8 FROM t1 WHERE 
+fruit_name = 'APPLE';
+SELECT @v5, @v6, @v7, @v8;
+
+SELECT DISTINCT @v5 + fruit_id, CONCAT(@v6, fruit_name) INTO @v9, @v10 FROM t1 
+WHERE fruit_name = 'APPLE';
+SELECT @v5, @v6, @v7, @v8, @v9, @v10;
+
+SELECT DISTINCT @v11:= @v5 + fruit_id, @v12:= CONCAT(@v6, fruit_name) INTO 
+@v13, @v14 FROM t1 WHERE fruit_name = 'APPLE';
+SELECT @v11, @v12, @v13, @v14;
+
+SELECT DISTINCT @v13, @v14 INTO @v15, @v16 FROM t1 WHERE fruit_name = 'APPLE';
+SELECT @v15, @v16;
+
+SELECT DISTINCT 2 + 2, 'Bob' INTO @v17, @v18 FROM t1 WHERE fruit_name = 
+'APPLE';
+SELECT @v17, @v18;
+
+--disable_warnings
+DROP TABLE IF EXISTS t2;
+--enable_warnings
+
+CREATE TABLE t2 (fruit_id INT NOT NULL, fruit_name varchar(20)
+default NULL);
+
+SELECT DISTINCT fruit_id, fruit_name INTO OUTFILE 
+'../tmp/data1.tmp' FROM t1 WHERE fruit_name = 'APPLE';
+LOAD DATA INFILE '../tmp/data1.tmp' INTO TABLE t2;
+--exec rm $MYSQL_TEST_DIR/var/tmp/data1.tmp
+
+SELECT DISTINCT @v19:= fruit_id, @v20:= fruit_name INTO OUTFILE 
+'../tmp/data2.tmp' FROM t1 WHERE fruit_name = 'APPLE';
+LOAD DATA INFILE '../tmp/data2.tmp' INTO TABLE t2;
+--exec rm $MYSQL_TEST_DIR/var/tmp/data2.tmp
+
+SELECT @v19, @v20;
+SELECT * FROM t2;
+
+DROP TABLE t1;
+DROP TABLE t2;
+
 # End of 4.1 tests