BUG#8804: wrong results for NULL IN (SELECT ...)

Evaluate "NULL IN (SELECT ...)" in a special way: Disable pushed-down 
conditions and their "consequences": 
 = Do full table scans instead of unique_[index_subquery] lookups.
 = Change appropriate "ref_or_null" accesses to full table scans in
   subquery's joins.
Also cache value of NULL IN (SELECT ...) if the SELECT is not correlated 
wrt any upper select.


mysql-test/r/subselect.result:
  BUG#8804: wrong results for NULL IN (SELECT ...): 
   - Updated test results
sql/item.h:
  BUG#8804: wrong results for NULL IN (SELECT ...): 
   - Added comments
sql/item_cmpfunc.cc:
  BUG#8804: wrong results for NULL IN (SELECT ...): 
  Made Item_in_optimizer to:
  - cache the value of "NULL IN (uncorrelated select)"
  - Turn off pushed-down predicates when evaluating "NULL IN (SELECT ...)"
sql/item_cmpfunc.h:
  BUG#8804: wrong results for NULL IN (SELECT ...): 
  - Made Item_in_optimizer cache the value of "NULL IN (uncorrelated select)"
  - Added comments
sql/item_subselect.cc:
  BUG#8804: wrong results for NULL IN (SELECT ...):
  - When needed, wrap the predicates we push into subquery into an 
    Item_func_trig_cond so we're able to turn them off when evaluating 
    NULL IN (SELECT ...).
  - Added code to evaluate NULL IN (SELECT ...) in a special way:
    = In [unique_]index_subquery, do full table scan to see if there 
      are any rows.
    = For other subqueries, change ref[_or_null] to ALL if the
      ref[_or_null] was created from pushed-down predicate.
sql/item_subselect.h:
  BUG#8804: wrong results for NULL IN (SELECT ...):
  - Added Item_subselect::is_correlated
  - Added comments
sql/records.cc:
  BUG#8804: wrong results for NULL IN (SELECT ...):
  - Make rr_sequential() non-static
sql/sql_lex.cc:
  BUG#8804: wrong results for NULL IN (SELECT ...):
  - Added st_select_lex::is_correlated and Item_subselect::is_correlated.
sql/sql_lex.h:
  BUG#8804: wrong results for NULL IN (SELECT ...):
  - Added st_select_lex::is_correlated
sql/sql_select.cc:
  BUG#8804: wrong results for NULL IN (SELECT ...):
  - Added KEY_FIELD::outer_ref to keep track of which ref accesses are 
    created from predicates that were pushed down into the subquery.
sql/sql_select.h:
  BUG#8804: wrong results for NULL IN (SELECT ...):
  - Added KEYUSE::outer_ref
mysql-test/r/subselect3.result:
  New BitKeeper file ``mysql-test/r/subselect3.result''
mysql-test/t/subselect3.test:
  New BitKeeper file ``mysql-test/t/subselect3.test''

3 files changed, 295 insertions, 5 deletions

diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result
index 55d48030a07..82c70e19f9c 100644
--- a/mysql-test/r/subselect.result
+++ b/mysql-test/r/subselect.result
@@ -744,7 +744,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 3	DEPENDENT UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
 NULL	UNION RESULT	<union2,3>	ALL	NULL	NULL	NULL	NULL	NULL	
 Warnings:
-Note	1003	select `test`.`t2`.`id` AS `id` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`id`,<exists>(select 1 AS `1` having (<cache>(`test`.`t2`.`id`) = <ref_null_helper>(1)) union select 3 AS `3` having (<cache>(`test`.`t2`.`id`) = <ref_null_helper>(3))))
+Note	1003	select `test`.`t2`.`id` AS `id` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`id`,<exists>(select 1 AS `1` having trigcond((<cache>(`test`.`t2`.`id`) = <ref_null_helper>(1))) union select 3 AS `3` having trigcond((<cache>(`test`.`t2`.`id`) = <ref_null_helper>(3)))))
 SELECT * FROM t2 WHERE id IN (SELECT 5 UNION SELECT 3);
 id
 SELECT * FROM t2 WHERE id IN (SELECT 5 UNION SELECT 2);
@@ -907,7 +907,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 2	DEPENDENT SUBQUERY	t2	ref_or_null	a	a	5	func	2	Using where; Using index
 2	DEPENDENT SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	3	Using where
 Warnings:
-Note	1003	select `test`.`t1`.`a` AS `a`,<in_optimizer>(`test`.`t1`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t2` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t2`.`a`) and ((<cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`) or isnull(`test`.`t2`.`a`))) having <is_not_null_test>(`test`.`t2`.`a`))) AS `t1.a in (select t2.a from t2,t3 where t3.a=t2.a)` from `test`.`t1`
+Note	1003	select `test`.`t1`.`a` AS `a`,<in_optimizer>(`test`.`t1`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t2` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t2`.`a`) and trigcond(((<cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`) or isnull(`test`.`t2`.`a`)))) having trigcond(<is_not_null_test>(`test`.`t2`.`a`)))) AS `t1.a in (select t2.a from t2,t3 where t3.a=t2.a)` from `test`.`t1`
 drop table t1,t2,t3;
 create table t1 (a float);
 select 10.5 IN (SELECT * from t1 LIMIT 1);
@@ -2817,19 +2817,19 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	8	
 2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	9	Using where
 Warnings:
-Note	1003	select `test`.`t1`.`one` AS `one`,`test`.`t1`.`two` AS `two`,<in_optimizer>((`test`.`t1`.`one`,`test`.`t1`.`two`),<exists>(select `test`.`t2`.`one` AS `one`,`test`.`t2`.`two` AS `two` from `test`.`t2` where ((`test`.`t2`.`flag` = _latin1'0') and ((<cache>(`test`.`t1`.`one`) = `test`.`t2`.`one`) or isnull(`test`.`t2`.`one`)) and ((<cache>(`test`.`t1`.`two`) = `test`.`t2`.`two`) or isnull(`test`.`t2`.`two`))) having (<is_not_null_test>(`test`.`t2`.`one`) and <is_not_null_test>(`test`.`t2`.`two`)))) AS `test` from `test`.`t1`
+Note	1003	select `test`.`t1`.`one` AS `one`,`test`.`t1`.`two` AS `two`,<in_optimizer>((`test`.`t1`.`one`,`test`.`t1`.`two`),<exists>(select `test`.`t2`.`one` AS `one`,`test`.`t2`.`two` AS `two` from `test`.`t2` where ((`test`.`t2`.`flag` = _latin1'0') and trigcond((((<cache>(`test`.`t1`.`one`) = `test`.`t2`.`one`) or isnull(`test`.`t2`.`one`)) and ((<cache>(`test`.`t1`.`two`) = `test`.`t2`.`two`) or isnull(`test`.`t2`.`two`))))) having trigcond((<is_not_null_test>(`test`.`t2`.`one`) and <is_not_null_test>(`test`.`t2`.`two`))))) AS `test` from `test`.`t1`
 explain extended SELECT one,two from t1 where ROW(one,two) IN (SELECT one,two FROM t2 WHERE flag = 'N');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	8	Using where
 2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	9	Using where
 Warnings:
-Note	1003	select `test`.`t1`.`one` AS `one`,`test`.`t1`.`two` AS `two` from `test`.`t1` where <in_optimizer>((`test`.`t1`.`one`,`test`.`t1`.`two`),<exists>(select `test`.`t2`.`one` AS `one`,`test`.`t2`.`two` AS `two` from `test`.`t2` where ((`test`.`t2`.`flag` = _latin1'N') and (<cache>(`test`.`t1`.`one`) = `test`.`t2`.`one`) and (<cache>(`test`.`t1`.`two`) = `test`.`t2`.`two`))))
+Note	1003	select `test`.`t1`.`one` AS `one`,`test`.`t1`.`two` AS `two` from `test`.`t1` where <in_optimizer>((`test`.`t1`.`one`,`test`.`t1`.`two`),<exists>(select `test`.`t2`.`one` AS `one`,`test`.`t2`.`two` AS `two` from `test`.`t2` where ((`test`.`t2`.`flag` = _latin1'N') and trigcond(((<cache>(`test`.`t1`.`one`) = `test`.`t2`.`one`) and (<cache>(`test`.`t1`.`two`) = `test`.`t2`.`two`))))))
 explain extended SELECT one,two,ROW(one,two) IN (SELECT one,two FROM t2 WHERE flag = '0' group by one,two) as 'test' from t1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	8	
 2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	9	Using where; Using temporary; Using filesort
 Warnings:
-Note	1003	select `test`.`t1`.`one` AS `one`,`test`.`t1`.`two` AS `two`,<in_optimizer>((`test`.`t1`.`one`,`test`.`t1`.`two`),<exists>(select `test`.`t2`.`one` AS `one`,`test`.`t2`.`two` AS `two` from `test`.`t2` where (`test`.`t2`.`flag` = _latin1'0') group by `test`.`t2`.`one`,`test`.`t2`.`two` having (((<cache>(`test`.`t1`.`one`) = `test`.`t2`.`one`) or isnull(`test`.`t2`.`one`)) and ((<cache>(`test`.`t1`.`two`) = `test`.`t2`.`two`) or isnull(`test`.`t2`.`two`)) and <is_not_null_test>(`test`.`t2`.`one`) and <is_not_null_test>(`test`.`t2`.`two`)))) AS `test` from `test`.`t1`
+Note	1003	select `test`.`t1`.`one` AS `one`,`test`.`t1`.`two` AS `two`,<in_optimizer>((`test`.`t1`.`one`,`test`.`t1`.`two`),<exists>(select `test`.`t2`.`one` AS `one`,`test`.`t2`.`two` AS `two` from `test`.`t2` where (`test`.`t2`.`flag` = _latin1'0') group by `test`.`t2`.`one`,`test`.`t2`.`two` having trigcond((((<cache>(`test`.`t1`.`one`) = `test`.`t2`.`one`) or isnull(`test`.`t2`.`one`)) and ((<cache>(`test`.`t1`.`two`) = `test`.`t2`.`two`) or isnull(`test`.`t2`.`two`)) and <is_not_null_test>(`test`.`t2`.`one`) and <is_not_null_test>(`test`.`t2`.`two`))))) AS `test` from `test`.`t1`
 DROP TABLE t1,t2;
 CREATE TABLE t1 (a char(5), b char(5));
 INSERT INTO t1 VALUES (NULL,'aaa'), ('aaa','aaa');
diff --git a/mysql-test/r/subselect3.result b/mysql-test/r/subselect3.result
new file mode 100644
index 00000000000..5ab8e448b39
--- /dev/null
+++ b/mysql-test/r/subselect3.result
@@ -0,0 +1,153 @@
+drop table if exists t0, t1, t2, t3, t4;
+create table t1 (oref int, grp int, ie int) ;
+insert into t1 (oref, grp, ie) values
+(1, 1, 1),
+(1, 1, 1),
+(1, 2, NULL),
+(2, 1, 3),
+(3, 1, 4),
+(3, 2, NULL);
+create table t2 (oref int, a int);
+insert into t2 values 
+(1, 1),
+(2, 2),
+(3, 3),
+(4, NULL),
+(2, NULL);
+select a, oref, a in (select max(ie) 
+from t1 where oref=t2.oref group by grp) from t2;
+a	oref	a in (select max(ie) 
+from t1 where oref=t2.oref group by grp)
+1	1	1
+2	2	0
+3	3	NULL
+NULL	4	0
+NULL	2	NULL
+explain extended
+select a, oref, a in (select max(ie) 
+from t1 where oref=t2.oref group by grp) from t2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	5	
+2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	6	Using where; Using temporary; Using filesort
+Warnings:
+Note	1276	Field or reference 't2.oref' of SELECT #2 was resolved in SELECT #1
+Note	1003	select `test`.`t2`.`a` AS `a`,`test`.`t2`.`oref` AS `oref`,<in_optimizer>(`test`.`t2`.`a`,<exists>(select max(`test`.`t1`.`ie`) AS `max(ie)` from `test`.`t1` where (`test`.`t1`.`oref` = `test`.`t2`.`oref`) group by `test`.`t1`.`grp` having trigcond((<cache>(`test`.`t2`.`a`) = <ref_null_helper>(max(`test`.`t1`.`ie`)))))) AS `a in (select max(ie) 
+from t1 where oref=t2.oref group by grp)` from `test`.`t2`
+explain extended
+select a, oref from t2 
+where a in (select max(ie) from t1 where oref=t2.oref group by grp);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	5	Using where
+2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	6	Using where; Using temporary; Using filesort
+Warnings:
+Note	1276	Field or reference 't2.oref' of SELECT #2 was resolved in SELECT #1
+Note	1003	select `test`.`t2`.`a` AS `a`,`test`.`t2`.`oref` AS `oref` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(select max(`test`.`t1`.`ie`) AS `max(ie)` from `test`.`t1` where (`test`.`t1`.`oref` = `test`.`t2`.`oref`) group by `test`.`t1`.`grp` having (<cache>(`test`.`t2`.`a`) = <ref_null_helper>(max(`test`.`t1`.`ie`)))))
+create table t3 (a int);
+insert into t3 values (NULL), (NULL);
+flush status;
+select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
+a in (select max(ie) from t1 where oref=4 group by grp)
+0
+0
+show status like 'Handler_read_rnd_next';
+Variable_name	Value
+Handler_read_rnd_next	11
+select ' ^ This must show 11' Z;
+Z
+ ^ This must show 11
+explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	
+2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	6	Using where; Using temporary; Using filesort
+Warnings:
+Note	1003	select <in_optimizer>(`test`.`t3`.`a`,<exists>(select max(`test`.`t1`.`ie`) AS `max(ie)` from `test`.`t1` where (`test`.`t1`.`oref` = 4) group by `test`.`t1`.`grp` having trigcond((<cache>(`test`.`t3`.`a`) = <ref_null_helper>(max(`test`.`t1`.`ie`)))))) AS `a in (select max(ie) from t1 where oref=4 group by grp)` from `test`.`t3`
+drop table t1, t2, t3;
+create table t1 (a int, oref int, key(a));
+insert into t1 values 
+(1, 1),
+(1, NULL),
+(2, 3),
+(2, NULL),
+(3, NULL);
+create table t2 (a int, oref int);
+insert into t2 values (1, 1), (2,2), (NULL, 3), (NULL, 4);
+select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2;
+oref	a	Z
+1	1	1
+2	2	0
+3	NULL	NULL
+4	NULL	0
+explain extended 
+select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	4	
+2	DEPENDENT SUBQUERY	t1	index_subquery	a	a	5	func	2	Using index; Using where
+Warnings:
+Note	1276	Field or reference 't2.oref' of SELECT #2 was resolved in SELECT #1
+Note	1003	select `test`.`t2`.`oref` AS `oref`,`test`.`t2`.`a` AS `a`,<in_optimizer>(`test`.`t2`.`a`,<exists>(<index_lookup>(<cache>(`test`.`t2`.`a`) in t1 on a checking NULL where (`test`.`t1`.`oref` = `test`.`t2`.`oref`)))) AS `Z` from `test`.`t2`
+flush status;
+select oref, a from t2 where a in (select a from t1 where oref=t2.oref);
+oref	a
+1	1
+show status like '%Handler_read_rnd_next';
+Variable_name	Value
+Handler_read_rnd_next	5
+delete from t2;
+insert into t2 values (NULL, 0),(NULL, 0), (NULL, 0), (NULL, 0);
+flush status;
+select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2;
+oref	a	Z
+0	NULL	0
+0	NULL	0
+0	NULL	0
+0	NULL	0
+show status like '%Handler_read%';
+Variable_name	Value
+Handler_read_first	0
+Handler_read_key	0
+Handler_read_next	0
+Handler_read_prev	0
+Handler_read_rnd	0
+Handler_read_rnd_next	29
+select 'No key lookups, seq reads: 29= 5 reads from t2 + 4 * 6 reads from t1.' Z;
+Z
+No key lookups, seq reads: 29= 5 reads from t2 + 4 * 6 reads from t1.
+drop table t1, t2;
+create table t1 (a int, b int, primary key (a));
+insert into t1 values (1,1), (3,1),(100,1);
+create table t2 (a int, b int);
+insert into t2 values (1,1),(2,1),(NULL,1),(NULL,0);
+select a,b, a in (select a from t1 where t1.b = t2.b) Z from t2 ;
+a	b	Z
+1	1	1
+2	1	0
+NULL	1	NULL
+NULL	0	0
+drop table t1, t2;
+create table t1 (a int, b int, key(a));
+insert into t1 values 
+(0,0),(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9);
+create table t2 like t1;
+insert into t2 select * from t1;
+update t2 set b=1;
+create table t3 (a int, oref int);
+insert into t3 values (1, 1), (NULL,1), (NULL,0);
+select a, oref, 
+t3.a in (select t1.a from t1, t2 where t1.b=t2.a and t2.b=t3.oref) Z 
+from t3;
+a	oref	Z
+1	1	1
+NULL	1	NULL
+NULL	0	0
+explain extended
+select a, oref, 
+t3.a in (select t1.a from t1, t2 where t1.b=t2.a and t2.b=t3.oref) Z 
+from t3;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	3	
+2	DEPENDENT SUBQUERY	t1	ref_or_null	a	a	5	func	4	Using where
+2	DEPENDENT SUBQUERY	t2	ref	a	a	5	test.t1.b	1	Using where
+Warnings:
+Note	1276	Field or reference 't3.oref' of SELECT #2 was resolved in SELECT #1
+Note	1003	select `test`.`t3`.`a` AS `a`,`test`.`t3`.`oref` AS `oref`,<in_optimizer>(`test`.`t3`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`a` = `test`.`t1`.`b`) and (`test`.`t2`.`b` = `test`.`t3`.`oref`) and trigcond(((<cache>(`test`.`t3`.`a`) = `test`.`t1`.`a`) or isnull(`test`.`t1`.`a`)))) having trigcond(<is_not_null_test>(`test`.`t1`.`a`)))) AS `Z` from `test`.`t3`
+drop table t1, t2, t3;
diff --git a/mysql-test/t/subselect3.test b/mysql-test/t/subselect3.test
new file mode 100644
index 00000000000..f7fbafdd17f
--- /dev/null
+++ b/mysql-test/t/subselect3.test
@@ -0,0 +1,137 @@
+--disable_warnings
+drop table if exists t0, t1, t2, t3, t4;
+--enable_warnings
+
+#
+# 1. Subquery with GROUP/HAVING
+#
+create table t1 (oref int, grp int, ie int) ;
+insert into t1 (oref, grp, ie) values
+ (1, 1, 1),
+ (1, 1, 1),
+ (1, 2, NULL),
+
+ (2, 1, 3),
+
+ (3, 1, 4),
+ (3, 2, NULL);
+
+#  Ok, for  
+#   select max(ie) from t1 where oref=PARAM group by grp
+# we'll have:
+#  1  ->  (1, NULL)    matching + NULL
+#  2  ->  (3)          non-matching
+#  3  ->  (3, NULL)    non-matching + NULL
+#  4  ->  ()           nothing.
+
+create table t2 (oref int, a int);
+insert into t2 values 
+  (1, 1),
+  (2, 2),
+  (3, 3),
+  (4, NULL),
+  (2, NULL);
+
+# true, false, null, false, null
+select a, oref, a in (select max(ie) 
+  from t1 where oref=t2.oref group by grp) from t2;
+
+# This must have a trigcond
+explain extended
+select a, oref, a in (select max(ie) 
+  from t1 where oref=t2.oref group by grp) from t2;
+
+# This must not have a trigcond:
+explain extended
+select a, oref from t2 
+where a in (select max(ie) from t1 where oref=t2.oref group by grp);
+
+
+# Non-correlated subquery, 2 NULL evaluations
+create table t3 (a int);
+insert into t3 values (NULL), (NULL);
+flush status;
+select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
+show status like 'Handler_read_rnd_next';
+select ' ^ This must show 11' Z;
+
+# This must show trigcond:
+explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
+
+drop table t1, t2, t3;
+
+# 
+#  2. Subquery handled with 'index_subquery':
+# 
+create table t1 (a int, oref int, key(a));
+insert into t1 values 
+  (1, 1),
+  (1, NULL),
+  (2, 3),
+  (2, NULL),
+  (3, NULL);
+
+create table t2 (a int, oref int);
+insert into t2 values (1, 1), (2,2), (NULL, 3), (NULL, 4);
+
+select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2;
+
+# The next explain shows "using index" but that is just incorrect display
+# (there is a bug filed about this).
+explain extended 
+select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2;
+
+flush status;
+select oref, a from t2 where a in (select a from t1 where oref=t2.oref);
+# This will only show access to t2:
+show status like '%Handler_read_rnd_next';
+
+# Check that repeated NULL-scans are not cached (subq. is not correlated):
+delete from t2;
+insert into t2 values (NULL, 0),(NULL, 0), (NULL, 0), (NULL, 0);
+
+flush status;
+select oref, a, a in (select a from t1 where oref=t2.oref) Z from t2;
+show status like '%Handler_read%';
+select 'No key lookups, seq reads: 29= 5 reads from t2 + 4 * 6 reads from t1.' Z;
+
+drop table t1, t2;
+
+#
+# 3. Subquery handled with 'unique_index_subquery':
+#
+create table t1 (a int, b int, primary key (a));
+insert into t1 values (1,1), (3,1),(100,1);
+
+create table t2 (a int, b int);
+insert into t2 values (1,1),(2,1),(NULL,1),(NULL,0);
+
+select a,b, a in (select a from t1 where t1.b = t2.b) Z from t2 ;
+
+drop table t1, t2;
+
+#
+# 4. Subquery that is a join, with ref access
+#
+create table t1 (a int, b int, key(a));
+insert into t1 values 
+  (0,0),(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9);
+
+create table t2 like t1;
+insert into t2 select * from t1;
+update t2 set b=1;
+
+create table t3 (a int, oref int);
+insert into t3 values (1, 1), (NULL,1), (NULL,0);
+select a, oref, 
+       t3.a in (select t1.a from t1, t2 where t1.b=t2.a and t2.b=t3.oref) Z 
+from t3;
+
+# This must have trigcond in WHERE and HAVING:
+explain extended
+select a, oref, 
+       t3.a in (select t1.a from t1, t2 where t1.b=t2.a and t2.b=t3.oref) Z 
+from t3;
+
+drop table t1, t2, t3;
+