drop table if exists t1,t11,t12,t2;
CREATE TABLE t1 (a tinyint(3), b tinyint(5));
INSERT INTO t1 VALUES (1,1);
INSERT LOW_PRIORITY INTO t1 VALUES (1,2);
INSERT INTO t1 VALUES (1,3);
DELETE from t1 where a=1 limit 1;
DELETE LOW_PRIORITY from t1 where a=1;
INSERT INTO t1 VALUES (1,1);
DELETE from t1;
LOCK TABLE t1 write;
INSERT INTO t1 VALUES (1,2);
DELETE from t1;
UNLOCK TABLES;
INSERT INTO t1 VALUES (1,2);
SET AUTOCOMMIT=0;
DELETE from t1;
SET AUTOCOMMIT=1;
drop table t1;
create table t1 (a bigint not null, primary key (a,a,a,a,a,a,a,a,a,a));
insert into t1 values (2),(4),(6),(8),(10),(12),(14),(16),(18),(20),(22),(24),(26),(23);
delete from t1 where a=26;
drop table t1;
create table t1 (a bigint not null, primary key (a,a,a,a,a,a,a,a,a,a));
insert into t1 values (2),(4),(6),(8),(10),(12),(14),(16),(18),(20),(22),(24),(26),(23),(27);
delete from t1 where a=27;
drop table t1;
CREATE TABLE `t1` (
`i` int(10) NOT NULL default '0',
`i2` int(10) NOT NULL default '0',
PRIMARY KEY  (`i`)
);
DELETE FROM t1 USING t1 WHERE post='1';
ERROR 42S22: Unknown column 'post' in 'where clause'
drop table t1;
CREATE TABLE t1 (
bool     char(0) default NULL,
not_null varchar(20) binary NOT NULL default '',
misc     integer not null,
PRIMARY KEY  (not_null)
) ENGINE=MyISAM;
INSERT INTO t1 VALUES (NULL,'a',4), (NULL,'b',5), (NULL,'c',6), (NULL,'d',7);
select * from t1 where misc > 5 and bool is null;
bool	not_null	misc
NULL	c	6
NULL	d	7
delete   from t1 where misc > 5 and bool is null;
select * from t1 where misc > 5 and bool is null;
bool	not_null	misc
select count(*) from t1;
count(*)
2
delete from t1 where 1 > 2;
select count(*) from t1;
count(*)
2
delete from t1 where 3 > 2;
select count(*) from t1;
count(*)
0
drop table t1;
create table t1 (a int not null auto_increment primary key, b char(32));
insert into t1 (b) values ('apple'), ('apple');
select * from t1;
a	b
1	apple
2	apple
delete t1 from t1, t1 as t2 where t1.b = t2.b and t1.a > t2.a;
select * from t1;
a	b
1	apple
drop table t1;
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),(0, 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
0	11
2	12
select * from t2;
a	b
1	21
2	12
3	23
delete t11.*, t12.* from t11,t12 where t11.a = t12.a and t11.b <> (select b from t2 where t11.a < t2.a);
ERROR 21000: Subquery returns more than 1 row
select * from t11;
a	b
0	10
1	11
2	12
select * from t12;
a	b
33	10
0	11
2	12
delete ignore t11.*, t12.* from t11,t12 where t11.a = t12.a and t11.b <> (select b from t2 where t11.a < t2.a);
Warnings:
Error	1242	Subquery returns more than 1 row
Error	1242	Subquery returns more than 1 row
select * from t11;
a	b
0	10
1	11
select * from t12;
a	b
33	10
0	11
insert into t11 values (2, 12);
delete from t11 where t11.b <> (select b from t2 where t11.a < t2.a);
ERROR 21000: Subquery returns more than 1 row
select * from t11;
a	b
0	10
1	11
2	12
delete ignore from t11 where t11.b <> (select b from t2 where t11.a < t2.a);
Warnings:
Error	1242	Subquery returns more than 1 row
Error	1242	Subquery returns more than 1 row
select * from t11;
a	b
0	10
1	11
drop table t11, t12, t2;
create table t1 (a int, b int, unique key (a), key (b));
insert into t1 values (3, 3), (7, 7);
delete t1 from t1 where a = 3;
check table t1;
Table	Op	Msg_type	Msg_text
test.t1	check	status	OK
select * from t1;
a	b
7	7
drop table t1;