Fixed LP BUG#747278

The problem was that when we have single row subquery with no rows
Item_cache(es) which represent result row was not null and being
requested via element_index() returned random value.

The fix is setting all Item_cache(es) in NULL before executing the
query (reset() method) which guaranty NULL value of whole query
or its elements requested in any way if no rows was found.

set_null() method was added to Item_cache to guaranty correct NULL
value in case of reseting the cache.

mysql-test/r/subselect.result

@@ -5734,4 +5734,85 @@ SELECT 't'
 b	a	b
 set @@join_cache_level= @save_join_cache_level;
 drop table t1,t2;
+#
+# LP BUG#747278 incorrect values of the NULL (no rows) single 
+# row subquery requested via element_index() interface
+#
+CREATE TABLE t1 (f1a int, f1b int) ;
+INSERT IGNORE INTO t1 VALUES (1,1),(2,2);
+CREATE TABLE t2 ( f2 int);
+INSERT IGNORE INTO t2 VALUES (3),(4);
+CREATE TABLE t3 (f3a int default 1, f3b int default 2);
+INSERT INTO t3 VALUES (1,1),(2,2);
+set @old_optimizer_switch = @@session.optimizer_switch;
+set @@optimizer_switch='materialization=on,partial_match_rowid_merge=on,partial_match_table_scan=off,subquery_cache=off,semijoin=off';
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+set @@session.optimizer_switch=@old_optimizer_switch;
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+select (null, null) = (null, null);
+(null, null) = (null, null)
+NULL
+SELECT (SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0);
+(SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0)
+NULL
+drop tables t1,t2,t3;
+# return optimizer switch changed in the beginning of this test
 set optimizer_switch=@subselect_tmp;

mysql-test/r/subselect_no_mat.result

@@ -5733,6 +5733,87 @@ SELECT 't'
 b	a	b
 set @@join_cache_level= @save_join_cache_level;
 drop table t1,t2;
+#
+# LP BUG#747278 incorrect values of the NULL (no rows) single 
+# row subquery requested via element_index() interface
+#
+CREATE TABLE t1 (f1a int, f1b int) ;
+INSERT IGNORE INTO t1 VALUES (1,1),(2,2);
+CREATE TABLE t2 ( f2 int);
+INSERT IGNORE INTO t2 VALUES (3),(4);
+CREATE TABLE t3 (f3a int default 1, f3b int default 2);
+INSERT INTO t3 VALUES (1,1),(2,2);
+set @old_optimizer_switch = @@session.optimizer_switch;
+set @@optimizer_switch='materialization=on,partial_match_rowid_merge=on,partial_match_table_scan=off,subquery_cache=off,semijoin=off';
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+set @@session.optimizer_switch=@old_optimizer_switch;
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+select (null, null) = (null, null);
+(null, null) = (null, null)
+NULL
+SELECT (SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0);
+(SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0)
+NULL
+drop tables t1,t2,t3;
+# return optimizer switch changed in the beginning of this test
 set optimizer_switch=@subselect_tmp;
 set optimizer_switch=default;
 select @@optimizer_switch like '%materialization=on%';

mysql-test/r/subselect_no_opts.result

@@ -5729,5 +5729,86 @@ SELECT 't'
 b	a	b
 set @@join_cache_level= @save_join_cache_level;
 drop table t1,t2;
+#
+# LP BUG#747278 incorrect values of the NULL (no rows) single 
+# row subquery requested via element_index() interface
+#
+CREATE TABLE t1 (f1a int, f1b int) ;
+INSERT IGNORE INTO t1 VALUES (1,1),(2,2);
+CREATE TABLE t2 ( f2 int);
+INSERT IGNORE INTO t2 VALUES (3),(4);
+CREATE TABLE t3 (f3a int default 1, f3b int default 2);
+INSERT INTO t3 VALUES (1,1),(2,2);
+set @old_optimizer_switch = @@session.optimizer_switch;
+set @@optimizer_switch='materialization=on,partial_match_rowid_merge=on,partial_match_table_scan=off,subquery_cache=off,semijoin=off';
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+set @@session.optimizer_switch=@old_optimizer_switch;
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+select (null, null) = (null, null);
+(null, null) = (null, null)
+NULL
+SELECT (SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0);
+(SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0)
+NULL
+drop tables t1,t2,t3;
+# return optimizer switch changed in the beginning of this test
 set optimizer_switch=@subselect_tmp;
 set @optimizer_switch_for_subselect_test=null;

mysql-test/r/subselect_no_scache.result

@@ -5738,6 +5738,87 @@ SELECT 't'
 b	a	b
 set @@join_cache_level= @save_join_cache_level;
 drop table t1,t2;
+#
+# LP BUG#747278 incorrect values of the NULL (no rows) single 
+# row subquery requested via element_index() interface
+#
+CREATE TABLE t1 (f1a int, f1b int) ;
+INSERT IGNORE INTO t1 VALUES (1,1),(2,2);
+CREATE TABLE t2 ( f2 int);
+INSERT IGNORE INTO t2 VALUES (3),(4);
+CREATE TABLE t3 (f3a int default 1, f3b int default 2);
+INSERT INTO t3 VALUES (1,1),(2,2);
+set @old_optimizer_switch = @@session.optimizer_switch;
+set @@optimizer_switch='materialization=on,partial_match_rowid_merge=on,partial_match_table_scan=off,subquery_cache=off,semijoin=off';
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+set @@session.optimizer_switch=@old_optimizer_switch;
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+select (null, null) = (null, null);
+(null, null) = (null, null)
+NULL
+SELECT (SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0);
+(SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0)
+NULL
+drop tables t1,t2,t3;
+# return optimizer switch changed in the beginning of this test
 set optimizer_switch=@subselect_tmp;
 set optimizer_switch=default;
 select @@optimizer_switch like '%subquery_cache=on%';

mysql-test/r/subselect_no_semijoin.result

@@ -5729,5 +5729,86 @@ SELECT 't'
 b	a	b
 set @@join_cache_level= @save_join_cache_level;
 drop table t1,t2;
+#
+# LP BUG#747278 incorrect values of the NULL (no rows) single 
+# row subquery requested via element_index() interface
+#
+CREATE TABLE t1 (f1a int, f1b int) ;
+INSERT IGNORE INTO t1 VALUES (1,1),(2,2);
+CREATE TABLE t2 ( f2 int);
+INSERT IGNORE INTO t2 VALUES (3),(4);
+CREATE TABLE t3 (f3a int default 1, f3b int default 2);
+INSERT INTO t3 VALUES (1,1),(2,2);
+set @old_optimizer_switch = @@session.optimizer_switch;
+set @@optimizer_switch='materialization=on,partial_match_rowid_merge=on,partial_match_table_scan=off,subquery_cache=off,semijoin=off';
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+set @@session.optimizer_switch=@old_optimizer_switch;
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1)
+NULL
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+(SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+(SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+NULL
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+(SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1)
+NULL
+select (null, null) = (null, null);
+(null, null) = (null, null)
+NULL
+SELECT (SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0);
+(SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0)
+NULL
+drop tables t1,t2,t3;
+# return optimizer switch changed in the beginning of this test
 set optimizer_switch=@subselect_tmp;
 set @optimizer_switch_for_subselect_test=null;

mysql-test/t/subselect.test

@@ -4840,4 +4840,49 @@ WHERE t2.b IN (
 
 set @@join_cache_level= @save_join_cache_level;
 drop table t1,t2;
+
+--echo #
+--echo # LP BUG#747278 incorrect values of the NULL (no rows) single 
+--echo # row subquery requested via element_index() interface
+--echo #
+
+CREATE TABLE t1 (f1a int, f1b int) ;
+INSERT IGNORE INTO t1 VALUES (1,1),(2,2);
+CREATE TABLE t2 ( f2 int);
+INSERT IGNORE INTO t2 VALUES (3),(4);
+CREATE TABLE t3 (f3a int default 1, f3b int default 2);
+INSERT INTO t3 VALUES (1,1),(2,2);
+
+# check different IN with switches where the bug was found
+set @old_optimizer_switch = @@session.optimizer_switch;
+set @@optimizer_switch='materialization=on,partial_match_rowid_merge=on,partial_match_table_scan=off,subquery_cache=off,semijoin=off';
+
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+
+set @@session.optimizer_switch=@old_optimizer_switch;
+
+# check different IN with default switches
+SELECT (SELECT f3a FROM t3 where f3a > 3) NOT IN (SELECT f1a FROM t1) FROM t2;
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) NOT IN (SELECT f1a,f1a FROM t1) FROM t2;
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1) FROM t2;
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) NOT IN (SELECT f1a, f1b FROM t1);
+SELECT (SELECT f3a FROM t3 where f3a > 3) IN (SELECT f1a FROM t1) FROM t2;
+SELECT (SELECT f3a,f3a  FROM t3 where f3a > 3) IN (SELECT f1a,f1a FROM t1) FROM t2;
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1) FROM t2;
+SELECT (SELECT f3a, f3b FROM t3 where f3a > 3) IN (SELECT f1a, f1b FROM t1);
+
+# other row operation with NULL single row subquery also should work
+select (null, null) = (null, null);
+SELECT (SELECT f3a, f3a FROM t3  where f3a > 3) = (0, 0);
+
+drop tables t1,t2,t3;
+
+--echo # return optimizer switch changed in the beginning of this test
 set optimizer_switch=@subselect_tmp;

sql/item.cc

@@ -8201,6 +8201,20 @@ void Item_cache::print(String *str, enum_query_type query_type)
   str->append(')');
 }
 
+/**
+  Assign to this cache NULL value if it is possible
+*/
+
+void Item_cache::set_null()
+{
+  if (maybe_null)
+  {
+    null_value= TRUE;
+    value_cached= TRUE;
+  }
+}
+
+
 bool  Item_cache_int::cache_value()
 {
   if (!example)
@@ -8671,6 +8685,20 @@ void Item_cache_row::bring_value()
 }
 
 
+/**
+  Assign to this cache NULL value if it is possible
+*/
+
+void Item_cache_row::set_null()
+{
+  Item_cache::set_null();
+  if (!values)
+    return;
+  for (uint i= 0; i < item_count; i++)
+    values[i]->set_null();
+};
+
+
 Item_type_holder::Item_type_holder(THD *thd, Item *item)
   :Item(thd, item), enum_set_typelib(0), fld_type(get_real_type(item))
 {

sql/item.h

@@ -3651,6 +3651,7 @@ class Item_cache: public Item_basic_constant
       return false;
     return example->is_expensive_processor(arg);
   }
+  virtual void set_null();
 };
 
 
@@ -3825,6 +3826,7 @@ class Item_cache_row: public Item_cache
     DBUG_VOID_RETURN;
   }
   bool cache_value();
+  virtual void set_null();
 };
 
 

sql/item_subselect.cc

@@ -893,7 +893,10 @@ void Item_singlerow_subselect::reset()
 {
   Item_subselect::reset();
   if (value)
-    value->null_value= TRUE;
+  {
+    for(uint i= 0; i < engine->cols(); i++)
+      row[i]->set_null();
+  }
 }
 
 
@@ -1004,6 +1007,11 @@ void Item_singlerow_subselect::fix_length_and_dec()
   */
   if (engine->no_tables())
     maybe_null= engine->may_be_null();
+  else
+  {
+    for (uint i= 0; i < max_columns; i++)
+      row[i]->maybe_null= TRUE;
+  }
 }
 
 

sql/sql_view.cc

@@ -1691,6 +1691,8 @@ frm_type_enum mysql_frm_type(THD *thd, char *path, enum legacy_db_type *dbt)
 
   *dbt= DB_TYPE_UNKNOWN;
 
+
+
   if ((file= my_open(path, O_RDONLY | O_SHARE, MYF(0))) < 0)
     DBUG_RETURN(FRMTYPE_ERROR);
   error= my_read(file, (uchar*) header, sizeof(header), MYF(MY_NABP));