mariadb/mysql-test/r/subselect.result

select (select 2);
(select 2)
2
explain select (select 2);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
Warnings:
Note	1247	Select 2 was reduced during optimisation
SELECT (SELECT 1) UNION SELECT (SELECT 2);
(SELECT 1)
1
2
explain SELECT (SELECT 1) UNION SELECT (SELECT 2);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
3	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
Warnings:
Note	1247	Select 2 was reduced during optimisation
Note	1247	Select 4 was reduced during optimisation
SELECT (SELECT (SELECT 0 UNION SELECT 0));
(SELECT (SELECT 0 UNION SELECT 0))
0
explain SELECT (SELECT (SELECT 0 UNION SELECT 0));
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
3	SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
4	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
Warnings:
Note	1247	Select 2 was reduced during optimisation
SELECT (SELECT 1 FROM (SELECT 1) as b HAVING a=1) as a;
Reference 'a' not supported (forward reference in item list)
SELECT (SELECT 1 FROM (SELECT 1) as b HAVING b=1) as a,(SELECT 1 FROM (SELECT 1) as c HAVING a=1) as b;
Reference 'b' not supported (forward reference in item list)
SELECT (SELECT 1),MAX(1) FROM (SELECT 1) as a;
(SELECT 1)	MAX(1)
1	1
SELECT (SELECT a) as a;
Reference 'a' not supported (forward reference in item list)
EXPLAIN SELECT 1 FROM (SELECT 1 as a) as b  HAVING (SELECT a)=1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	<derived2>	system	NULL	NULL	NULL	NULL	1	
3	DEPENDENT SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
2	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
SELECT 1 FROM (SELECT 1 as a) as b HAVING (SELECT a)=1;
1
1
SELECT (SELECT 1), a;
Unknown column 'a' in 'field list'
SELECT 1 as a FROM (SELECT 1) as b HAVING (SELECT a)=1;
a
1
SELECT 1 FROM (SELECT (SELECT a) b) c;
Unknown column 'a' in 'field list'
SELECT * FROM (SELECT 1 as id) b WHERE id IN (SELECT * FROM (SELECT 1 as id) c ORDER BY id);
id
1
SELECT * FROM (SELECT 1) a  WHERE 1 IN (SELECT 1,1);
Cardinality error (more/less than 1 columns)
SELECT 1 IN (SELECT 1);
1 IN (SELECT 1)
1
SELECT 1 FROM (SELECT 1 as a) b WHERE 1 IN (SELECT (SELECT a));
1
1
select (SELECT 1 FROM (SELECT 1) a PROCEDURE ANALYSE(1));
Wrong usage of PROCEDURE and subquery
SELECT 1 FROM (SELECT 1) a PROCEDURE ANALYSE((SELECT 1));
Incorrect parameters to procedure 'ANALYSE'
SELECT (SELECT 1) as a FROM (SELECT 1) b WHERE (SELECT a) IS NULL;
a
SELECT (SELECT 1) as a FROM (SELECT 1) b WHERE (SELECT a) IS NOT NULL;
a
1
SELECT (SELECT 1,2,3) = ROW(1,2,3);
(SELECT 1,2,3) = ROW(1,2,3)
1
SELECT (SELECT 1,2,3) = ROW(1,2,1);
(SELECT 1,2,3) = ROW(1,2,1)
0
SELECT (SELECT 1,2,3) < ROW(1,2,1);
(SELECT 1,2,3) < ROW(1,2,1)
0
SELECT (SELECT 1,2,3) > ROW(1,2,1);
(SELECT 1,2,3) > ROW(1,2,1)
1
SELECT (SELECT 1,2,3) = ROW(1,2,NULL);
(SELECT 1,2,3) = ROW(1,2,NULL)
NULL
SELECT ROW(1,2,3) = (SELECT 1,2,3);
ROW(1,2,3) = (SELECT 1,2,3)
1
SELECT ROW(1,2,3) = (SELECT 1,2,1);
ROW(1,2,3) = (SELECT 1,2,1)
0
SELECT ROW(1,2,3) < (SELECT 1,2,1);
ROW(1,2,3) < (SELECT 1,2,1)
0
SELECT ROW(1,2,3) > (SELECT 1,2,1);
ROW(1,2,3) > (SELECT 1,2,1)
1
SELECT ROW(1,2,3) = (SELECT 1,2,NULL);
ROW(1,2,3) = (SELECT 1,2,NULL)
NULL
SELECT (SELECT 1.5,2,'a') = ROW(1.5,2,'a');
(SELECT 1.5,2,'a') = ROW(1.5,2,'a')
1
SELECT (SELECT 1.5,2,'a') = ROW(1.5,2,'b');
(SELECT 1.5,2,'a') = ROW(1.5,2,'b')
0
SELECT (SELECT 1.5,2,'a') = ROW('b',2,'b');
(SELECT 1.5,2,'a') = ROW('b',2,'b')
0
SELECT (SELECT 'b',2,'a') = ROW(1.5,2,'a');
(SELECT 'b',2,'a') = ROW(1.5,2,'a')
0
SELECT (SELECT 1.5,2,'a') = ROW(1.5,'c','a');
(SELECT 1.5,2,'a') = ROW(1.5,'c','a')
0
SELECT (SELECT 1.5,'c','a') = ROW(1.5,2,'a');
(SELECT 1.5,'c','a') = ROW(1.5,2,'a')
0
drop table if exists t1,t2,t3,t4,t5,t6,t7,t8;
create table t1 (a int);
create table t2 (a int, b int);
create table t3 (a int);
create table t4 (a int, b int);
insert into t1 values (2);
insert into t2 values (1,7),(2,7);
insert into t4 values (4,8),(3,8),(5,9);
select (select a from t1 where t1.a = a1) as a2, (select b from t2 where t2.b=a2) as a1;
Reference 'a1' not supported (forward reference in item list)
select (select a from t1 where t1.a=t2.a), a from t2;
(select a from t1 where t1.a=t2.a)	a
NULL	1
2	2
select (select a from t1 where t1.a=t2.b), a from t2;
(select a from t1 where t1.a=t2.b)	a
NULL	1
NULL	2
select (select a from t1), a from t2;
(select a from t1)	a
2	1
2	2
select (select a from t3), a from t2;
(select a from t3)	a
NULL	1
NULL	2
select * from t2 where t2.a=(select a from t1);
a	b
2	7
insert into t3 values (6),(7),(3);
select * from t2 where t2.b=(select a from t3 order by 1 desc limit 1);
a	b
1	7
2	7
(select * from t2 where t2.b=(select a from t3 order by 1 desc limit 1))
union (select * from t4 order by a limit 2) limit 3;
a	b
1	7
2	7
3	8
(select * from t2 where t2.b=(select a from t3 order by 1 desc limit 1))
union (select * from t4 where t4.b=(select max(t2.a)*4 from t2) order by a);
a	b
1	7
2	7
3	8
4	8
explain (select * from t2 where t2.b=(select a from t3 order by 1 desc limit 1))
union (select * from t4 where t4.b=(select max(t2.a)*4 from t2) order by a);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	Using where
2	SUBSELECT	t3	ALL	NULL	NULL	NULL	NULL	3	Using filesort
3	UNION	t4	ALL	NULL	NULL	NULL	NULL	3	Using where; Using filesort
4	SUBSELECT	t2	ALL	NULL	NULL	NULL	NULL	2	
select (select a from t3 where a<t2.a*4 order by 1 desc limit 1), a from t2;
(select a from t3 where a<t2.a*4 order by 1 desc limit 1)	a
3	1
7	2
select (select t3.a from t3 where a<8 order by 1 desc limit 1), a from 
(select * from t2 where a>1) as tt;
(select t3.a from t3 where a<8 order by 1 desc limit 1)	a
7	2
explain select (select t3.a from t3 where a<8 order by 1 desc limit 1), a from 
(select * from t2 where a>1) as tt;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	<derived3>	system	NULL	NULL	NULL	NULL	1	
3	DERIVED	t2	ALL	NULL	NULL	NULL	NULL	2	Using where
2	SUBSELECT	t3	ALL	NULL	NULL	NULL	NULL	3	Using where; Using filesort
select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from t3) order by 1 desc limit 1);
a
2
select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from t3 where t3.a > t1.a) order by 1 desc limit 1);
a
2
select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from t3 where t3.a < t1.a) order by 1 desc limit 1);
a
select b,(select avg(t2.a+(select min(t3.a) from t3 where t3.a >= t4.a)) from t2) from t4;
b	(select avg(t2.a+(select min(t3.a) from t3 where t3.a >= t4.a)) from t2)
8	7.5000
8	4.5000
9	7.5000
explain select b,(select avg(t2.a+(select min(t3.a) from t3 where t3.a >= t4.a)) from t2) from t4;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t4	ALL	NULL	NULL	NULL	NULL	3	
2	DEPENDENT SUBSELECT	t2	ALL	NULL	NULL	NULL	NULL	2	
3	DEPENDENT SUBSELECT	t3	ALL	NULL	NULL	NULL	NULL	3	Using where
select * from t3 where exists (select * from t2 where t2.b=t3.a);
a
7
select * from t3 where not exists (select * from t2 where t2.b=t3.a);
a
6
3
select * from t3 where a in (select b from t2);
a
7
select * from t3 where a not in (select b from t2);
a
6
3
select * from t3 where a = some (select b from t2);
a
7
select * from t3 where a <> any (select b from t2);
a
6
3
select * from t3 where a = all (select b from t2);
a
7
select * from t3 where a <> all (select b from t2);
a
6
3
insert into t2 values (100, 5);
select * from t3 where a < any (select b from t2);
a
6
3
select * from t3 where a < all (select b from t2);
a
3
select * from t3 where a >= any (select b from t2);
a
6
7
select * from t3 where a >= all (select b from t2);
a
7
delete from t2 where a=100;
select * from t3 where a in (select a,b from t2);
Cardinality error (more/less than 1 columns)
select * from t3 where a in (select * from t2);
Cardinality error (more/less than 1 columns)
insert into t4 values (12,7),(1,7),(10,9),(9,6),(7,6),(3,9);
select b,max(a) as ma from t4 group by b having b < (select max(t2.a)
from t2 where t2.b=t4.b);
b	ma
select b,max(a) as ma from t4 group by b having b >= (select max(t2.a)
from t2 where t2.b=t4.b);
b	ma
7	12
create table t5 (a int);
select (select a from t1 where t1.a=t2.a union select a from t5 where t5.a=t2.a), a from t2;
(select a from t1 where t1.a=t2.a union select a from t5 where t5.a=t2.a)	a
NULL	1
2	2
insert into t5 values (5);
select (select a from t1 where t1.a=t2.a union select a from t5 where t5.a=t2.a), a from t2;
(select a from t1 where t1.a=t2.a union select a from t5 where t5.a=t2.a)	a
NULL	1
2	2
insert into t5 values (2);
select (select a from t1 where t1.a=t2.a union select a from t5 where t5.a=t2.a), a from t2;
(select a from t1 where t1.a=t2.a union select a from t5 where t5.a=t2.a)	a
NULL	1
2	2
explain select (select a from t1 where t1.a=t2.a union select a from t5 where t5.a=t2.a), a from t2;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	
2	DEPENDENT SUBSELECT	t1	system	NULL	NULL	NULL	NULL	1	Using where
3	DEPENDENT UNION	t5	ALL	NULL	NULL	NULL	NULL	2	Using where
select (select a from t1 where t1.a=t2.a union all select a from t5 where t5.a=t2.a), a from t2;
Subselect returns more than 1 record
create table t6 (patient_uq int, clinic_uq int, index i1 (clinic_uq));
create table t7( uq int primary key, name char(25));
insert into t7 values(1,"Oblastnaia bolnitsa"),(2,"Bolnitsa Krasnogo Kresta");
insert into t6 values (1,1),(1,2),(2,2),(1,3);
select * from t6 where exists (select * from t7 where uq = clinic_uq);
patient_uq	clinic_uq
1	1
1	2
2	2
select * from t1 where a= (select a from t2,t4 where t2.b=t4.b);
Column: 'a' in field list is ambiguous
drop table if exists t1,t2,t3;
CREATE TABLE t3 (a varchar(20),b char(1) NOT NULL default '0');
INSERT INTO t3 VALUES ('W','a'),('A','c'),('J','b');
CREATE TABLE t2 (a varchar(20),b int NOT NULL default '0');
INSERT INTO t2 VALUES ('W','1'),('A','3'),('J','2');
CREATE TABLE t1 (a varchar(20),b date NOT NULL default '0000-00-00');
INSERT INTO t1 VALUES ('W','1732-02-22'),('A','1735-10-30'),('J','1743-04-13');
SELECT * FROM t1 WHERE b = (SELECT MIN(b) FROM t1);
a	b
W	1732-02-22
SELECT * FROM t2 WHERE b = (SELECT MIN(b) FROM t2);
a	b
W	1
SELECT * FROM t3 WHERE b = (SELECT MIN(b) FROM t3);
a	b
W	a
drop table if exists t8;
CREATE TABLE `t8` (
`pseudo` varchar(35) character set latin1 NOT NULL default '',
`email` varchar(60) character set latin1 NOT NULL default '',
PRIMARY KEY  (`pseudo`),
UNIQUE KEY `email` (`email`)
) TYPE=MyISAM CHARSET=latin1 ROW_FORMAT=DYNAMIC;
INSERT INTO t8 (pseudo,email) VALUES ('joce','test');
INSERT INTO t8 (pseudo,email) VALUES ('joce1','test1');
INSERT INTO t8 (pseudo,email) VALUES ('2joce1','2test1');
EXPLAIN SELECT pseudo,(SELECT email FROM t8 WHERE pseudo=(SELECT pseudo FROM t8 WHERE pseudo='joce')) FROM t8 WHERE pseudo=(SELECT pseudo FROM t8 WHERE pseudo='joce');
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t8	const	PRIMARY	PRIMARY	35	const	1	
4	SUBSELECT	t8	const	PRIMARY	PRIMARY	35	const	1	
2	SUBSELECT	t8	const	PRIMARY	PRIMARY	35	const	1	
3	SUBSELECT	t8	const	PRIMARY	PRIMARY	35	const	1	
SELECT pseudo FROM t8 WHERE pseudo=(SELECT pseudo,email FROM
t8 WHERE pseudo='joce');
Cardinality error (more/less than 1 columns)
SELECT pseudo FROM t8 WHERE pseudo=(SELECT * FROM t8 WHERE
pseudo='joce');
Cardinality error (more/less than 1 columns)
SELECT pseudo FROM t8 WHERE pseudo=(SELECT pseudo FROM t8 WHERE pseudo='joce');
pseudo
joce
SELECT pseudo FROM t8 WHERE pseudo=(SELECT pseudo FROM t8 WHERE pseudo LIKE '%joce%');
Subselect returns more than 1 record
drop table if exists t1,t2,t3,t4,t5,t6,t7,t8;
CREATE TABLE `t1` (
`topic` mediumint(8) unsigned NOT NULL default '0',
`date` date NOT NULL default '0000-00-00',
`pseudo` varchar(35) character set latin1 NOT NULL default '',
PRIMARY KEY  (`pseudo`,`date`,`topic`),
KEY `topic` (`topic`)
) TYPE=MyISAM ROW_FORMAT=DYNAMIC;
INSERT INTO t1 (topic,date,pseudo) VALUES
('43506','2002-10-02','joce'),('40143','2002-08-03','joce');
EXPLAIN SELECT DISTINCT date FROM t1 WHERE date='2002-08-03';
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	index	NULL	PRIMARY	41	NULL	2	Using where; Using index
EXPLAIN SELECT (SELECT DISTINCT date FROM t1 WHERE date='2002-08-03');
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
2	SUBSELECT	t1	index	NULL	PRIMARY	41	NULL	2	Using where; Using index
SELECT DISTINCT date FROM t1 WHERE date='2002-08-03';
date
2002-08-03
SELECT (SELECT DISTINCT date FROM t1 WHERE date='2002-08-03');
(SELECT DISTINCT date FROM t1 WHERE date='2002-08-03')
2002-08-03
SELECT 1 FROM t1 WHERE 1=(SELECT 1 UNION SELECT 1) UNION ALL SELECT 1;
1
1
1
1
SELECT 1 FROM t1 WHERE 1=(SELECT 1 UNION ALL SELECT 1) UNION SELECT 1;
Subselect returns more than 1 record
EXPLAIN SELECT 1 FROM t1 WHERE 1=(SELECT 1 UNION SELECT 1);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	index	NULL	topic	3	NULL	2	Using index
2	SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
3	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
drop table t1;
CREATE TABLE `t1` (
`numeropost` mediumint(8) unsigned NOT NULL auto_increment,
`maxnumrep` int(10) unsigned NOT NULL default '0',
PRIMARY KEY  (`numeropost`),
UNIQUE KEY `maxnumrep` (`maxnumrep`)
) TYPE=MyISAM ROW_FORMAT=FIXED;
INSERT INTO t1 (numeropost,maxnumrep) VALUES (40143,1),(43506,2);
CREATE TABLE `t2` (
`mot` varchar(30) NOT NULL default '',
`topic` mediumint(8) unsigned NOT NULL default '0',
`date` date NOT NULL default '0000-00-00',
`pseudo` varchar(35) NOT NULL default '',
PRIMARY KEY  (`mot`,`pseudo`,`date`,`topic`)
) TYPE=MyISAM ROW_FORMAT=DYNAMIC;
INSERT INTO t2 (mot,topic,date,pseudo) VALUES ('joce','40143','2002-10-22','joce'), ('joce','43506','2002-10-22','joce');
select numeropost as a FROM t1 GROUP BY (SELECT 1 FROM t1 HAVING a=1);
a
40143
SELECT numeropost,maxnumrep FROM t1 WHERE exists (SELECT 1 FROM t2 WHERE (mot='joce') AND date >= '2002-10-21' AND t1.numeropost = t2.topic) ORDER BY maxnumrep DESC LIMIT 0, 20;
numeropost	maxnumrep
43506	2
40143	1
SELECT (SELECT 1) as a FROM (SELECT 1 FROM t1 HAVING a=1) b;
Unknown column 'a' in 'having clause'
SELECT 1 IN (SELECT 1 FROM t2 HAVING a);
Unknown column 'a' in 'having clause'
SELECT * from t2 where topic IN (SELECT topic FROM t2 GROUP BY date);
mot	topic	date	pseudo
joce	40143	2002-10-22	joce
joce	43506	2002-10-22	joce
SELECT * from t2 where topic IN (SELECT topic FROM t2 GROUP BY date HAVING topic < 4100);
mot	topic	date	pseudo
joce	43506	2002-10-22	joce
SELECT * from t2 where topic IN (SELECT SUM(topic) FROM t1);
mot	topic	date	pseudo
SELECT * from t2 where topic = any (SELECT topic FROM t2 GROUP BY date);
mot	topic	date	pseudo
joce	40143	2002-10-22	joce
joce	43506	2002-10-22	joce
SELECT * from t2 where topic = any (SELECT topic FROM t2 GROUP BY date HAVING topic < 4100);
mot	topic	date	pseudo
joce	43506	2002-10-22	joce
SELECT * from t2 where topic = any (SELECT SUM(topic) FROM t1);
mot	topic	date	pseudo
SELECT * from t2 where topic = all (SELECT topic FROM t2 GROUP BY date);
mot	topic	date	pseudo
joce	40143	2002-10-22	joce
SELECT * from t2 where topic = all (SELECT topic FROM t2 GROUP BY date HAVING topic < 4100);
mot	topic	date	pseudo
joce	40143	2002-10-22	joce
SELECT * from t2 where topic = all (SELECT SUM(topic) FROM t2);
mot	topic	date	pseudo
SELECT * from t2 where topic <> any (SELECT SUM(topic) FROM t2);
mot	topic	date	pseudo
joce	40143	2002-10-22	joce
joce	43506	2002-10-22	joce
drop table t1,t2;
CREATE TABLE `t1` (
`numeropost` mediumint(8) unsigned NOT NULL auto_increment,
`maxnumrep` int(10) unsigned NOT NULL default '0',
PRIMARY KEY  (`numeropost`),
UNIQUE KEY `maxnumrep` (`maxnumrep`)
) TYPE=MyISAM ROW_FORMAT=FIXED;
INSERT INTO t1 (numeropost,maxnumrep) VALUES (1,0),(2,1);
select numeropost as a FROM t1 GROUP BY (SELECT 1 FROM t1 HAVING a=1);
Subselect returns more than 1 record
select numeropost as a FROM t1 ORDER BY (SELECT 1 FROM t1 HAVING a=1);
Subselect returns more than 1 record
drop table t1;
CREATE TABLE t1 (field char(1) NOT NULL DEFAULT 'b');
INSERT INTO t1 VALUES ();
SELECT field FROM t1 WHERE 1=(SELECT 1 UNION ALL SELECT 1 FROM (SELECT 1) a HAVING field='b');
Subselect returns more than 1 record
drop table t1;
CREATE TABLE `t1` (
`numeropost` mediumint(8) unsigned NOT NULL default '0',
`numreponse` int(10) unsigned NOT NULL auto_increment,
`pseudo` varchar(35) NOT NULL default '',
PRIMARY KEY  (`numeropost`,`numreponse`),
UNIQUE KEY `numreponse` (`numreponse`),
KEY `pseudo` (`pseudo`,`numeropost`)
) TYPE=MyISAM;
SELECT (SELECT numeropost FROM t1 HAVING numreponse=a),numreponse FROM (SELECT * FROM t1) as a;
Reference 'numreponse' not supported (forward reference in item list)
SELECT numreponse, (SELECT numeropost FROM t1 HAVING numreponse=a) FROM (SELECT * FROM t1) as a;
Unknown column 'a' in 'having clause'
SELECT numreponse, (SELECT numeropost FROM t1 HAVING numreponse=1) FROM (SELECT * FROM t1) as a;
numreponse	(SELECT numeropost FROM t1 HAVING numreponse=1)
INSERT INTO t1 (numeropost,numreponse,pseudo) VALUES (1,1,'joce'),(1,2,'joce'),(1,3,'test');
EXPLAIN SELECT numreponse FROM t1 WHERE numeropost='1' AND numreponse=(SELECT 1 FROM t1 WHERE numeropost='1');
Subselect returns more than 1 record
EXPLAIN SELECT MAX(numreponse) FROM t1 WHERE numeropost='1';
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
EXPLAIN SELECT numreponse FROM t1 WHERE numeropost='1' AND numreponse=(SELECT MAX(numreponse) FROM t1 WHERE numeropost='1');
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	const	PRIMARY,numreponse	PRIMARY	7	const,const	1	
2	SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
drop table t1;
CREATE TABLE t1 (a int(1));
INSERT INTO t1 VALUES (1);
SELECT 1 FROM (SELECT a FROM t1) b HAVING (SELECT b.a)=1;
1
1
drop table t1;
create table t1 (a int NOT NULL, b int, primary key (a));
create table t2 (a int NOT NULL, b int, primary key (a));
insert into t1 values (0, 10),(1, 11),(2, 12);
insert into t2 values (1, 21),(2, 22),(3, 23);
select * from t1;
a	b
0	10
1	11
2	12
update t1 set b= (select b from t1);
You can't specify target table 't1' for update in FROM clause
update t1 set b= (select b from t2);
Subselect returns more than 1 record
update t1 set b= (select b from t2 where t1.a = t2.a);
select * from t1;
a	b
0	NULL
1	21
2	22
drop table t1, t2;
create table t1 (a int NOT NULL, b int, primary key (a));
create table t2 (a int NOT NULL, b int, primary key (a));
insert into t1 values (0, 10),(1, 11),(2, 12);
insert into t2 values (1, 21),(2, 12),(3, 23);
select * from t1;
a	b
0	10
1	11
2	12
select * from t1 where b = (select b from t2 where t1.a = t2.a);
a	b
2	12
delete from t1 where b = (select b from t1);
You can't specify target table 't1' for update in FROM clause
delete from t1 where b = (select b from t2);
Subselect returns more than 1 record
delete from t1 where b = (select b from t2 where t1.a = t2.a);
select * from t1;
a	b
0	10
1	11
drop table t1, t2;
drop table if exists t11, t12, t2;
create table t11 (a int NOT NULL, b int, primary key (a));
create table t12 (a int NOT NULL, b int, primary key (a));
create table t2 (a int NOT NULL, b int, primary key (a));
insert into t11 values (0, 10),(1, 11),(2, 12);
insert into t12 values (33, 10),(22, 11),(2, 12);
insert into t2 values (1, 21),(2, 12),(3, 23);
select * from t11;
a	b
0	10
1	11
2	12
select * from t12;
a	b
33	10
22	11
2	12
delete t11.*, t12.* from t11,t12 where t11.a = t12.a and t11.b = (select b from t12 where t11.a = t12.a);
You can't specify target table 't12' for update in FROM clause
delete t11.*, t12.* from t11,t12 where t11.a = t12.a and t11.b = (select b from t2);
Subselect returns more than 1 record
delete t11.*, t12.* from t11,t12 where t11.a = t12.a and t11.b = (select b from t2 where t11.a = t2.a);
select * from t11;
a	b
0	10
1	11
select * from t12;
a	b
33	10
22	11
drop table t11, t12, t2;
CREATE TABLE t1 (x int);
create table t2 (a int);
create table t3 (a int);
insert into t2 values (1);
insert into t3 values (1),(2);
INSERT INTO t1 (x) VALUES ((SELECT x FROM t1));
You can't specify target table 't1' for update in FROM clause
INSERT INTO t1 (x) VALUES ((SELECT a FROM t3));
Subselect returns more than 1 record
INSERT INTO t1 (x) VALUES ((SELECT a FROM t2));
select * from t1;
x
1
insert into t2 values (1);
INSERT DELAYED INTO t1 (x) VALUES ((SELECT SUM(a) FROM t2));
select * from t1;
x
1
2
INSERT INTO t1 (x) select (SELECT SUM(a)+1 FROM t2) FROM t2;
select * from t1;
x
1
2
3
3
INSERT INTO t1 (x) select (SELECT SUM(x)+2 FROM t1) FROM t2;
You can't specify target table 't1' for update in FROM clause
INSERT DELAYED INTO t1 (x) VALUES ((SELECT SUM(x) FROM t2));
select * from t1;
x
1
2
3
3
0
drop table t1, t2, t3;
CREATE TABLE t1 (x int not null, y int, primary key (x));
create table t2 (a int);
create table t3 (a int);
insert into t2 values (1);
insert into t3 values (1),(2);
select * from t1;
x	y
replace into t1 (x, y) VALUES ((SELECT x FROM t1), (SELECT a+1 FROM t2));
You can't specify target table 't1' for update in FROM clause
replace into t1 (x, y) VALUES ((SELECT a FROM t3), (SELECT a+1 FROM t2));
Subselect returns more than 1 record
replace into t1 (x, y) VALUES ((SELECT a FROM t2), (SELECT a+1 FROM t2));
select * from t1;
x	y
1	2
replace into t1 (x, y) VALUES ((SELECT a FROM t2), (SELECT a+2 FROM t2));
select * from t1;
x	y
1	3
replace DELAYED into t1 (x, y) VALUES ((SELECT a+3 FROM t2), (SELECT a FROM t2));
select * from t1;
x	y
1	3
4	1
replace DELAYED into t1 (x, y) VALUES ((SELECT a+3 FROM t2), (SELECT a+1 FROM t2));
select * from t1;
x	y
1	3
4	2
replace LOW_PRIORITY into t1 (x, y) VALUES ((SELECT a+1 FROM t2), (SELECT a FROM t2));
select * from t1;
x	y
1	3
4	2
2	1
drop table t1, t2, t3;
SELECT * FROM (SELECT 1) b WHERE 1 IN (SELECT *);
No tables used
drop table if exists t;
CREATE TABLE t (id int(11) default NULL, KEY id (id)) TYPE=MyISAM CHARSET=latin1;
INSERT INTO t VALUES (1),(2);
SELECT * FROM t WHERE id IN (SELECT 1);
id
1
EXPLAIN SELECT * FROM t WHERE id IN (SELECT 1);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t	ref	id	id	5	const	1	Using where; Using index
Warnings:
Note	1247	Select 2 was reduced during optimisation
SELECT * FROM t WHERE id IN (SELECT 1 UNION SELECT 3);
id
1
SELECT * FROM t WHERE id IN (SELECT 1+(select 1));
id
2
EXPLAIN SELECT * FROM t WHERE id IN (SELECT 1+(select 1));
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t	ref	id	id	5	const	1	Using where; Using index
3	SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
Warnings:
Note	1247	Select 3 was reduced during optimisation
Note	1247	Select 2 was reduced during optimisation
EXPLAIN SELECT * FROM t WHERE id IN (SELECT 1 UNION SELECT 3);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t	index	NULL	id	5	NULL	2	Using where; Using index
2	DEPENDENT SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
3	DEPENDENT UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
SELECT * FROM t WHERE id IN (SELECT 5 UNION SELECT 3);
id
SELECT * FROM t WHERE id IN (SELECT 5 UNION SELECT 2);
id
2
INSERT INTO t VALUES ((SELECT * FROM t));
You can't specify target table 't' for update in FROM clause
SELECT * FROM t;
id
1
2
CREATE TABLE t1 (id int(11) default NULL, KEY id (id)) TYPE=MyISAM CHARSET=latin1;
INSERT INTO t1 values (1),(1);
UPDATE t SET id=(SELECT * FROM t1);
Subselect returns more than 1 record
drop table t, t1;
create table t (a int);
insert into t values (1),(2),(3);
select 1 IN (SELECT * from t);
1 IN (SELECT * from t)
1
select 10 IN (SELECT * from t);
10 IN (SELECT * from t)
0
select NULL IN (SELECT * from t);
NULL IN (SELECT * from t)
NULL
update t set a=NULL where a=2;
select 1 IN (SELECT * from t);
1 IN (SELECT * from t)
1
select 3 IN (SELECT * from t);
3 IN (SELECT * from t)
1
select 10 IN (SELECT * from t);
10 IN (SELECT * from t)
NULL
select 1 > ALL (SELECT * from t);
1 > ALL (SELECT * from t)
0
select 10 > ALL (SELECT * from t);
10 > ALL (SELECT * from t)
NULL
select 1 > ANY (SELECT * from t);
1 > ANY (SELECT * from t)
NULL
select 10 > ANY (SELECT * from t);
10 > ANY (SELECT * from t)
1
drop table t;
create table t (a varchar(20));
insert into t values ('A'),('BC'),('DEF');
select 'A' IN (SELECT * from t);
'A' IN (SELECT * from t)
1
select 'XYZS' IN (SELECT * from t);
'XYZS' IN (SELECT * from t)
0
select NULL IN (SELECT * from t);
NULL IN (SELECT * from t)
NULL
update t set a=NULL where a='BC';
select 'A' IN (SELECT * from t);
'A' IN (SELECT * from t)
1
select 'DEF' IN (SELECT * from t);
'DEF' IN (SELECT * from t)
1
select 'XYZS' IN (SELECT * from t);
'XYZS' IN (SELECT * from t)
NULL
select 'A' > ALL (SELECT * from t);
'A' > ALL (SELECT * from t)
0
select 'XYZS' > ALL (SELECT * from t);
'XYZS' > ALL (SELECT * from t)
NULL
select 'A' > ANY (SELECT * from t);
'A' > ANY (SELECT * from t)
NULL
select 'XYZS' > ANY (SELECT * from t);
'XYZS' > ANY (SELECT * from t)
1
drop table t;
create table t (a float);
insert into t values (1.5),(2.5),(3.5);
select 1.5 IN (SELECT * from t);
1.5 IN (SELECT * from t)
1
select 10.5 IN (SELECT * from t);
10.5 IN (SELECT * from t)
0
select NULL IN (SELECT * from t);
NULL IN (SELECT * from t)
NULL
update t set a=NULL where a=2.5;
select 1.5 IN (SELECT * from t);
1.5 IN (SELECT * from t)
1
select 3.5 IN (SELECT * from t);
3.5 IN (SELECT * from t)
1
select 10.5 IN (SELECT * from t);
10.5 IN (SELECT * from t)
NULL
select 1.5 > ALL (SELECT * from t);
1.5 > ALL (SELECT * from t)
0
select 10.5 > ALL (SELECT * from t);
10.5 > ALL (SELECT * from t)
NULL
select 1.5 > ANY (SELECT * from t);
1.5 > ANY (SELECT * from t)
NULL
select 10.5 > ANY (SELECT * from t);
10.5 > ANY (SELECT * from t)
1
explain select (select a+1) from t;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t	ALL	NULL	NULL	NULL	NULL	3	
Warnings:
Note	1247	Select 2 was reduced during optimisation
select (select a+1) from t;
(select a+1)
2.5
NULL
4.5
drop table t;
create table t (a float);
select 10.5 IN (SELECT * from t LIMIT 1);
This version of MySQL doesn't yet support 'LIMIT & IN/ALL/ANY/SOME subquery'
select 10.5 IN (SELECT * from t LIMIT 1 UNION SELECT 1.5);
This version of MySQL doesn't yet support 'LIMIT & IN/ALL/ANY/SOME subquery'
drop table t;
create table t1 (a int, b int, c varchar(10));
create table t2 (a int);
insert into t1 values (1,2,'a'),(2,3,'b'),(3,4,'c');
insert into t2 values (1),(2),(NULL);
select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,2,'a'),(select c from t1 where a=t2.a)  from t2;
a	(select a,b,c from t1 where t1.a=t2.a) = ROW(a,2,'a')	(select c from t1 where a=t2.a)
1	1	a
2	0	b
NULL	NULL	NULL
select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,3,'b'),(select c from t1 where a=t2.a) from t2;
a	(select a,b,c from t1 where t1.a=t2.a) = ROW(a,3,'b')	(select c from t1 where a=t2.a)
1	0	a
2	1	b
NULL	NULL	NULL
select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,4,'c'),(select c from t1 where a=t2.a) from t2;
a	(select a,b,c from t1 where t1.a=t2.a) = ROW(a,4,'c')	(select c from t1 where a=t2.a)
1	0	a
2	0	b
NULL	NULL	NULL
drop table t1,t2;
drop table if exists t;
create table t (a int, b real, c varchar(10));
insert into t values (1, 1, 'a'), (2,2,'b'), (NULL, 2, 'b');
select ROW(1, 1, 'a') IN (select a,b,c from t);
ROW(1, 1, 'a') IN (select a,b,c from t)
1
select ROW(1, 2, 'a') IN (select a,b,c from t);
ROW(1, 2, 'a') IN (select a,b,c from t)
NULL
select ROW(1, 1, 'a') IN (select b,a,c from t);
ROW(1, 1, 'a') IN (select b,a,c from t)
1
select ROW(1, 1, 'a') IN (select a,b,c from t where a is not null);
ROW(1, 1, 'a') IN (select a,b,c from t where a is not null)
1
select ROW(1, 2, 'a') IN (select a,b,c from t where a is not null);
ROW(1, 2, 'a') IN (select a,b,c from t where a is not null)
0
select ROW(1, 1, 'a') IN (select b,a,c from t where a is not null);
ROW(1, 1, 'a') IN (select b,a,c from t where a is not null)
1
select ROW(1, 1, 'a') IN (select a,b,c from t where c='b' or c='a');
ROW(1, 1, 'a') IN (select a,b,c from t where c='b' or c='a')
1
select ROW(1, 2, 'a') IN (select a,b,c from t where c='b' or c='a');
ROW(1, 2, 'a') IN (select a,b,c from t where c='b' or c='a')
NULL
select ROW(1, 1, 'a') IN (select b,a,c from t where c='b' or c='a');
ROW(1, 1, 'a') IN (select b,a,c from t where c='b' or c='a')
1
select ROW(1, 1, 'a') IN (select b,a,c from t limit 2);
This version of MySQL doesn't yet support 'LIMIT & IN/ALL/ANY/SOME subquery'
drop table t;
create table t (a int);
insert into t values (1);
do @a:=(SELECT a from t);
select @a;
@a
1
drop table t;
do (SELECT a from t);
Table 'test.t' doesn't exist