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drop table if exists t1,t2,t3,t11,t12;
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,
b bigint not null default 0,
c bigint not null default 0,
d bigint not null default 0,
e bigint not null default 0,
f bigint not null default 0,
g bigint not null default 0,
h bigint not null default 0,
i bigint not null default 0,
j bigint not null default 0,
primary key (a,b,c,d,e,f,g,h,i,j));
insert into t1 (a) 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,
b bigint not null default 0,
c bigint not null default 0,
d bigint not null default 0,
e bigint not null default 0,
f bigint not null default 0,
g bigint not null default 0,
h bigint not null default 0,
i bigint not null default 0,
j bigint not null default 0,
primary key (a,b,c,d,e,f,g,h,i,j));
insert into t1 (a) 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;
CREATE TABLE t1 ( a int PRIMARY KEY );
DELETE FROM t1 WHERE t1.a > 0 ORDER BY t1.a;
INSERT INTO t1 VALUES (0),(1),(2);
DELETE FROM t1 WHERE t1.a > 0 ORDER BY t1.a LIMIT 1;
SELECT * FROM t1;
a
0
2
DROP TABLE t1;
create table t1 (a int);
delete `4.t1` from t1 as `4.t1` where `4.t1`.a = 5;
delete FROM `4.t1` USING t1 as `4.t1` where `4.t1`.a = 5;
drop table t1;
CREATE TABLE t1 (a int not null,b int not null);
CREATE TABLE t2 (a int not null, b int not null, primary key (a,b));
CREATE TABLE t3 (a int not null, b int not null, primary key (a,b));
insert into t1 values (1,1),(2,1),(1,3);
insert into t2 values (1,1),(2,2),(3,3);
insert into t3 values (1,1),(2,1),(1,3);
select * from t1,t2,t3 where t1.a=t2.a AND t2.b=t3.a and t1.b=t3.b;
a b a b a b
1 1 1 1 1 1
2 1 2 2 2 1
1 3 1 1 1 3
explain select * from t1,t2,t3 where t1.a=t2.a AND t2.b=t3.a and t1.b=t3.b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 ref PRIMARY PRIMARY 4 test.t1.a 1 Using index
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 8 test.t2.b,test.t1.b 1 Using index
delete t2.*,t3.* from t1,t2,t3 where t1.a=t2.a AND t2.b=t3.a and t1.b=t3.b;
select * from t3;
a b
drop table t1,t2,t3;
create table t1(a date not null);
insert into t1 values (0);
select * from t1 where a is null;
a
0000-00-00
delete from t1 where a is null;
select count(*) from t1;
count(*)
0
drop table t1;
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