drop table if exists t1,t2,t3; drop database if exists mysqltest; drop view if exists v1; revoke all privileges on mysqltest.t1 from mysqltest_1@localhost; revoke all privileges on mysqltest.* from mysqltest_1@localhost; delete from mysql.user where user=_binary'mysqltest_1'; create table t1(id1 int not null auto_increment primary key, t char(12)); create table t2(id2 int not null, t char(12)); create table t3(id3 int not null, t char(12), index(id3)); select count(*) from t1 where id1 > 95; count(*) 5 select count(*) from t2 where id2 > 95; count(*) 25 select count(*) from t3 where id3 > 95; count(*) 250 update t1,t2,t3 set t1.t="aaa", t2.t="bbb", t3.t="cc" where t1.id1 = t2.id2 and t2.id2 = t3.id3 and t1.id1 > 90; select count(*) from t1 where t = "aaa"; count(*) 10 select count(*) from t1 where id1 > 90; count(*) 10 select count(*) from t2 where t = "bbb"; count(*) 50 select count(*) from t2 where id2 > 90; count(*) 50 select count(*) from t3 where t = "cc"; count(*) 500 select count(*) from t3 where id3 > 90; count(*) 500 delete t1.*, t2.*, t3.* from t1,t2,t3 where t1.id1 = t2.id2 and t2.id2 = t3.id3 and t1.id1 > 95; check table t1, t2, t3; Table Op Msg_type Msg_text test.t1 check status OK test.t2 check status OK test.t3 check status OK select count(*) from t1 where id1 > 95; count(*) 0 select count(*) from t2 where id2 > 95; count(*) 0 select count(*) from t3 where id3 > 95; count(*) 0 delete t1, t2, t3 from t1,t2,t3 where t1.id1 = t2.id2 and t2.id2 = t3.id3 and t1.id1 > 5; select count(*) from t1 where id1 > 5; count(*) 0 select count(*) from t2 where id2 > 5; count(*) 0 select count(*) from t3 where id3 > 5; count(*) 0 delete from t1, t2, t3 using t1,t2,t3 where t1.id1 = t2.id2 and t2.id2 = t3.id3 and t1.id1 > 0; select count(*) from t1 where id1; count(*) 0 select count(*) from t2 where id2; count(*) 0 select count(*) from t3 where id3; count(*) 0 drop table t1,t2,t3; create table t1(id1 int not null primary key, t varchar(100)) pack_keys = 1; create table t2(id2 int not null, t varchar(100), index(id2)) pack_keys = 1; delete t1 from t1,t2 where t1.id1 = t2.id2 and t1.id1 > 500; drop table t1,t2; CREATE TABLE t1 ( id int(11) NOT NULL default '0', name varchar(10) default NULL, PRIMARY KEY (id) ) ENGINE=MyISAM; INSERT INTO t1 VALUES (1,'aaa'),(2,'aaa'),(3,'aaa'); CREATE TABLE t2 ( id int(11) NOT NULL default '0', name varchar(10) default NULL, PRIMARY KEY (id) ) ENGINE=MyISAM; INSERT INTO t2 VALUES (2,'bbb'),(3,'bbb'),(4,'bbb'); CREATE TABLE t3 ( id int(11) NOT NULL default '0', mydate datetime default NULL, PRIMARY KEY (id) ) ENGINE=MyISAM; INSERT INTO t3 VALUES (1,'2002-02-04 00:00:00'),(3,'2002-05-12 00:00:00'),(5,'2002-05-12 00:00:00'),(6,'2002-06-22 00:00:00'),(7,'2002-07-22 00:00:00'); delete t1,t2,t3 from t1,t2,t3 where to_days(now())-to_days(t3.mydate)>=30 and t3.id=t1.id and t3.id=t2.id; select * from t3; id mydate 1 2002-02-04 00:00:00 5 2002-05-12 00:00:00 6 2002-06-22 00:00:00 7 2002-07-22 00:00:00 DROP TABLE t1,t2,t3; CREATE TABLE IF NOT EXISTS `t1` ( `id` int(11) NOT NULL auto_increment, `tst` text, `tst1` text, PRIMARY KEY (`id`) ) ENGINE=MyISAM; CREATE TABLE IF NOT EXISTS `t2` ( `ID` int(11) NOT NULL auto_increment, `ParId` int(11) default NULL, `tst` text, `tst1` text, PRIMARY KEY (`ID`), KEY `IX_ParId_t2` (`ParId`), FOREIGN KEY (`ParId`) REFERENCES `t1` (`id`) ) ENGINE=MyISAM; INSERT INTO t1(tst,tst1) VALUES("MySQL","MySQL AB"), ("MSSQL","Microsoft"), ("ORACLE","ORACLE"); INSERT INTO t2(ParId) VALUES(1), (2), (3); select * from t2; ID ParId tst tst1 1 1 NULL NULL 2 2 NULL NULL 3 3 NULL NULL UPDATE t2, t1 SET t2.tst = t1.tst, t2.tst1 = t1.tst1 WHERE t2.ParId = t1.Id; select * from t2; ID ParId tst tst1 1 1 MySQL MySQL AB 2 2 MSSQL Microsoft 3 3 ORACLE ORACLE drop table t1, t2 ; create table t1 (n numeric(10)); create table t2 (n numeric(10)); insert into t2 values (1),(2),(4),(8),(16),(32); select * from t2 left outer join t1 using (n); n 1 2 4 8 16 32 delete t1,t2 from t2 left outer join t1 using (n); select * from t2 left outer join t1 using (n); n drop table t1,t2 ; create table t1 (n int(10) not null primary key, d int(10)); create table t2 (n int(10) not null primary key, d int(10)); insert into t1 values(1,1); insert into t2 values(1,10),(2,20); LOCK TABLES t1 write, t2 read; DELETE t1.*, t2.* FROM t1,t2 where t1.n=t2.n; ERROR HY000: Table 't2' was locked with a READ lock and can't be updated UPDATE t1,t2 SET t1.d=t2.d,t2.d=30 WHERE t1.n=t2.n; ERROR HY000: Table 't2' was locked with a READ lock and can't be updated UPDATE t1,t2 SET t1.d=t2.d WHERE t1.n=t2.n; unlock tables; LOCK TABLES t1 write, t2 write; UPDATE t1,t2 SET t1.d=t2.d WHERE t1.n=t2.n; select * from t1; n d 1 10 DELETE t1.*, t2.* FROM t1,t2 where t1.n=t2.n; select * from t1; n d select * from t2; n d 2 20 unlock tables; drop table t1,t2; set sql_safe_updates=1; create table t1 (n int(10), d int(10)); create table t2 (n int(10), d int(10)); insert into t1 values(1,1); insert into t2 values(1,10),(2,20); UPDATE t1,t2 SET t1.d=t2.d WHERE t1.n=t2.n; ERROR HY000: You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column set sql_safe_updates=0; drop table t1,t2; set timestamp=1038401397; create table t1 (n int(10) not null primary key, d int(10), t timestamp); create table t2 (n int(10) not null primary key, d int(10), t timestamp); insert into t1 values(1,1,NULL); insert into t2 values(1,10,NULL),(2,20,NULL); set timestamp=1038000000; UPDATE t1,t2 SET t1.d=t2.d WHERE t1.n=t2.n; select n,d,unix_timestamp(t) from t1; n d unix_timestamp(t) 1 10 1038000000 select n,d,unix_timestamp(t) from t2; n d unix_timestamp(t) 1 10 1038401397 2 20 1038401397 UPDATE t1,t2 SET 1=2 WHERE t1.n=t2.n; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '1=2 WHERE t1.n=t2.n' at line 1 drop table t1,t2; set timestamp=0; set sql_safe_updates=0; create table t1 (n int(10) not null primary key, d int(10)); create table t2 (n int(10) not null primary key, d int(10)); insert into t1 values(1,1), (3,3); insert into t2 values(1,10),(2,20); UPDATE t2 left outer join t1 on t1.n=t2.n SET t1.d=t2.d; select * from t1; n d 1 10 3 3 select * from t2; n d 1 10 2 20 drop table t1,t2; create table t1 (n int(10), d int(10)); create table t2 (n int(10), d int(10)); insert into t1 values(1,1),(1,2); insert into t2 values(1,10),(2,20); UPDATE t1,t2 SET t1.d=t2.d,t2.d=30 WHERE t1.n=t2.n; select * from t1; n d 1 10 1 10 select * from t2; n d 1 30 2 20 drop table t1,t2; create table t1 (n int(10), d int(10)); create table t2 (n int(10), d int(10)); insert into t1 values(1,1),(3,2); insert into t2 values(1,10),(1,20); UPDATE t1,t2 SET t1.d=t2.d,t2.d=30 WHERE t1.n=t2.n; select * from t1; n d 1 10 3 2 select * from t2; n d 1 30 1 30 UPDATE t1 a ,t2 b SET a.d=b.d,b.d=30 WHERE a.n=b.n; select * from t1; n d 1 30 3 2 select * from t2; n d 1 30 1 30 DELETE a, b FROM t1 a,t2 b where a.n=b.n; select * from t1; n d 3 2 select * from t2; n d drop table t1,t2; CREATE TABLE t1 ( broj int(4) unsigned NOT NULL default '0', naziv char(25) NOT NULL default 'NEPOZNAT', PRIMARY KEY (broj)) ENGINE=MyISAM; INSERT INTO t1 VALUES (1,'jedan'),(2,'dva'),(3,'tri'),(4,'xxxxxxxxxx'),(5,'a'),(10,''),(11,''),(12,''),(13,''); CREATE TABLE t2 ( broj int(4) unsigned NOT NULL default '0', naziv char(25) NOT NULL default 'NEPOZNAT', PRIMARY KEY (broj)) ENGINE=MyISAM; INSERT INTO t2 VALUES (1,'jedan'),(2,'dva'),(3,'tri'),(4,'xxxxxxxxxx'),(5,'a'); CREATE TABLE t3 ( broj int(4) unsigned NOT NULL default '0', naziv char(25) NOT NULL default 'NEPOZNAT', PRIMARY KEY (broj)) ENGINE=MyISAM; INSERT INTO t3 VALUES (1,'jedan'),(2,'dva'); update t1,t2 set t1.naziv="aaaa" where t1.broj=t2.broj; update t1,t2,t3 set t1.naziv="bbbb", t2.naziv="aaaa" where t1.broj=t2.broj and t2.broj=t3.broj; drop table t1,t2,t3; CREATE TABLE t1 (a int not null primary key, b int not null, key (b)); CREATE TABLE t2 (a int not null primary key, b int not null, key (b)); INSERT INTO t1 values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9); INSERT INTO t2 values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9); update t1,t2 set t1.a=t1.a+100; select * from t1; a b 101 1 102 2 103 3 104 4 105 5 106 6 107 7 108 8 109 9 update t1,t2 set t1.a=t1.a+100 where t1.a=101; select * from t1; a b 201 1 102 2 103 3 104 4 105 5 106 6 107 7 108 8 109 9 update t1,t2 set t1.b=t1.b+10 where t1.b=2; select * from t1; a b 201 1 102 12 103 3 104 4 105 5 106 6 107 7 108 8 109 9 update t1,t2 set t1.b=t1.b+2,t2.b=t1.b+10 where t1.b between 3 and 5 and t2.a=t1.a-100; select * from t1; a b 201 1 102 12 103 5 104 6 105 7 106 6 107 7 108 8 109 9 select * from t2; a b 1 1 2 2 3 13 4 14 5 15 6 6 7 7 8 8 9 9 update t1,t2 set t1.b=t2.b, t1.a=t2.a where t1.a=t2.a and not exists (select * from t2 where t2.a > 10); drop table t1,t2; CREATE TABLE t3 ( KEY1 varchar(50) NOT NULL default '', PARAM_CORR_DISTANCE_RUSH double default NULL, PARAM_CORR_DISTANCE_GEM double default NULL, PARAM_AVG_TARE double default NULL, PARAM_AVG_NB_DAYS double default NULL, PARAM_DEFAULT_PROP_GEM_SRVC varchar(50) default NULL, PARAM_DEFAULT_PROP_GEM_NO_ETIK varchar(50) default NULL, PARAM_SCENARIO_COSTS varchar(50) default NULL, PARAM_DEFAULT_WAGON_COST double default NULL, tmp int(11) default NULL, PRIMARY KEY (KEY1)) ENGINE=MyISAM; INSERT INTO t3 VALUES ('A',1,1,22,3.2,'R','R','BASE2',0.24,NULL); create table t1 (A varchar(1)); insert into t1 values ("A") ,("B"),("C"),("D"); create table t2(Z varchar(15)); insert into t2(Z) select concat(a.a,b.a,c.a,d.a) from t1 as a, t1 as b, t1 as c, t1 as d; update t2,t3 set Z =param_scenario_costs; drop table t1,t2,t3; create table t1 (a int, b int); create table t2 (a int, b int); insert into t1 values (1,1),(2,1),(3,1); insert into t2 values (1,1), (3,1); update t1 left join t2 on t1.a=t2.a set t1.b=2, t2.b=2 where t1.b=1 and t2.b=1 or t2.a is NULL; select t1.a, t1.b,t2.a, t2.b from t1 left join t2 on t1.a=t2.a where t1.b=1 and t2.b=1 or t2.a is NULL; a b a b 2 2 NULL NULL drop table t1,t2; create table t1 (a int not null auto_increment primary key, b int not null); insert into t1 (b) values (1),(2),(3),(4); update t1, t1 as t2 set t1.b=t2.b+1 where t1.a=t2.a; select * from t1; a b 1 2 2 3 3 4 4 5 drop table t1; create table t1(id1 smallint(5), field char(5)); create table t2(id2 smallint(5), field char(5)); insert into t1 values (1, 'a'), (2, 'aa'); insert into t2 values (1, 'b'), (2, 'bb'); select * from t1; id1 field 1 a 2 aa select * from t2; id2 field 1 b 2 bb update t2 inner join t1 on t1.id1=t2.id2 set t2.field=t1.field where 0=1; update t2, t1 set t2.field=t1.field where t1.id1=t2.id2 and 0=1; delete t1, t2 from t2 inner join t1 on t1.id1=t2.id2 where 0=1; delete t1, t2 from t2,t1 where t1.id1=t2.id2 and 0=1; drop table t1,t2; create table t1 ( a int not null, b int not null) ; alter table t1 add index i1(a); delete from t1 where a > 2000000; create table t2 like t1; insert into t2 select * from t1; select 't2 rows before small delete', count(*) from t1; t2 rows before small delete count(*) t2 rows before small delete 2000000 delete t1,t2 from t1,t2 where t1.b=t2.a and t1.a < 2; select 't2 rows after small delete', count(*) from t2; t2 rows after small delete count(*) t2 rows after small delete 1999999 select 't1 rows after small delete', count(*) from t1; t1 rows after small delete count(*) t1 rows after small delete 1999999 delete t1,t2 from t1,t2 where t1.b=t2.a and t1.a < 100*1000; select 't2 rows after big delete', count(*) from t2; t2 rows after big delete count(*) t2 rows after big delete 1900001 select 't1 rows after big delete', count(*) from t1; t1 rows after big delete count(*) t1 rows after big delete 1900001 drop table t1,t2; CREATE TABLE t1 ( a int ); CREATE TABLE t2 ( a int ); DELETE t1 FROM t1, t2 AS t3; DELETE t4 FROM t1, t1 AS t4; DELETE t3 FROM t1 AS t3, t1 AS t4; DELETE t1 FROM t1 AS t3, t2 AS t4; ERROR 42S02: Unknown table 't1' in MULTI DELETE INSERT INTO t1 values (1),(2); INSERT INTO t2 values (1),(2); DELETE t1 FROM t1 AS t2, t2 AS t1 where t1.a=t2.a and t1.a=1; SELECT * from t1; a 1 2 SELECT * from t2; a 2 DELETE t2 FROM t1 AS t2, t2 AS t1 where t1.a=t2.a and t1.a=2; SELECT * from t1; a 1 SELECT * from t2; a 2 DROP TABLE t1,t2; create table `t1` (`p_id` int(10) unsigned NOT NULL auto_increment, `p_code` varchar(20) NOT NULL default '', `p_active` tinyint(1) unsigned NOT NULL default '1', PRIMARY KEY (`p_id`) ); create table `t2` (`c2_id` int(10) unsigned NULL auto_increment, `c2_p_id` int(10) unsigned NOT NULL default '0', `c2_note` text NOT NULL, `c2_active` tinyint(1) unsigned NOT NULL default '1', PRIMARY KEY (`c2_id`), KEY `c2_p_id` (`c2_p_id`) ); insert into t1 values (0,'A01-Comp',1); insert into t1 values (0,'B01-Comp',1); insert into t2 values (0,1,'A Note',1); update t1 left join t2 on p_id = c2_p_id set c2_note = 'asdf-1' where p_id = 2; select * from t1; p_id p_code p_active 1 A01-Comp 1 2 B01-Comp 1 select * from t2; c2_id c2_p_id c2_note c2_active 1 1 A Note 1 drop table t1, t2; create database mysqltest; create table mysqltest.t1 (a int, b int, primary key (a)); create table mysqltest.t2 (a int, b int, primary key (a)); create table mysqltest.t3 (a int, b int, primary key (a)); grant select on mysqltest.* to mysqltest_1@localhost; grant update on mysqltest.t1 to mysqltest_1@localhost; update t1, t2 set t1.b=1 where t1.a=t2.a; update t1, t2 set t1.b=(select t3.b from t3 where t1.a=t3.a) where t1.a=t2.a; revoke all privileges on mysqltest.t1 from mysqltest_1@localhost; revoke all privileges on mysqltest.* from mysqltest_1@localhost; delete from mysql.user where user=_binary'mysqltest_1'; drop database mysqltest; create table t1 (a int, primary key (a)); create table t2 (a int, primary key (a)); create table t3 (a int, primary key (a)); delete t1,t3 from t1,t2 where t1.a=t2.a and t2.a=(select t3.a from t3 where t1.a=t3.a); ERROR 42S02: Unknown table 't3' in MULTI DELETE drop table t1, t2, t3; create table t1 (col1 int); create table t2 (col1 int); update t1,t2 set t1.col1 = (select max(col1) from t1) where t1.col1 = t2.col1; ERROR HY000: You can't specify target table 't1' for update in FROM clause delete t1 from t1,t2 where t1.col1 < (select max(col1) from t1) and t1.col1 = t2.col1; ERROR HY000: You can't specify target table 't1' for update in FROM clause drop table t1,t2; create table t1 ( aclid bigint not null primary key, status tinyint(1) not null ) engine = innodb; create table t2 ( refid bigint not null primary key, aclid bigint, index idx_acl(aclid) ) engine = innodb; insert into t2 values(1,null); delete t2, t1 from t2 left join t1 on (t2.aclid=t1.aclid) where t2.refid='1'; drop table t1, t2; create table t1(a int); create table t2(a int); delete from t1,t2 using t1,t2 where t1.a=(select a from t1); ERROR HY000: You can't specify target table 't1' for update in FROM clause drop table t1, t2; create table t1 ( c char(8) not null ) engine=innodb; insert into t1 values ('0'),('1'),('2'),('3'),('4'),('5'),('6'),('7'),('8'),('9'); insert into t1 values ('A'),('B'),('C'),('D'),('E'),('F'); alter table t1 add b char(8) not null; alter table t1 add a char(8) not null; alter table t1 add primary key (a,b,c); update t1 set a=c, b=c; create table t2 like t1; insert into t2 select * from t1; delete t1,t2 from t2,t1 where t1.a<'B' and t2.b=t1.b; drop table t1,t2; create table t1 ( c char(8) not null ) engine=innodb; insert into t1 values ('0'),('1'),('2'),('3'),('4'),('5'),('6'),('7'),('8'),('9'); insert into t1 values ('A'),('B'),('C'),('D'),('E'),('F'); alter table t1 add b char(8) not null; alter table t1 add a char(8) not null; alter table t1 add primary key (a,b,c); update t1 set a=c, b=c; create table t2 like t1; insert into t2 select * from t1; delete t1,t2 from t2,t1 where t1.a<'B' and t2.b=t1.b; drop table t1,t2; create table t1 (a int, b int); insert into t1 values (1, 2), (2, 3), (3, 4); create table t2 (a int); insert into t2 values (10), (20), (30); create view v1 as select a as b, a/10 as a from t2; lock table t1 write; alter table t1 add column c int default 100 after a; update t1, v1 set t1.b=t1.a+t1.b+v1.b where t1.a=v1.a; unlock tables; select * from t1; a c b 1 100 13 2 100 25 3 100 37 select * from t2; a 10 20 30 drop view v1; drop table t1, t2; create table t1 (i1 int, i2 int, i3 int); create table t2 (id int, c1 varchar(20), c2 varchar(20)); insert into t1 values (1,5,10),(3,7,12),(4,5,2),(9,10,15),(2,2,2); insert into t2 values (9,"abc","def"),(5,"opq","lmn"),(2,"test t","t test"); select * from t1 order by i1; i1 i2 i3 1 5 10 2 2 2 3 7 12 4 5 2 9 10 15 select * from t2; id c1 c2 9 abc def 5 opq lmn 2 test t t test update t1,t2 set t1.i2=15, t2.c2="ppc" where t1.i1=t2.id; select * from t1 order by i1; i1 i2 i3 1 5 10 2 15 2 3 7 12 4 5 2 9 15 15 select * from t2 order by id; id c1 c2 2 test t ppc 5 opq lmn 9 abc ppc delete t1.*,t2.* from t1,t2 where t1.i2=t2.id; select * from t1 order by i1; i1 i2 i3 2 15 2 3 7 12 9 15 15 select * from t2 order by id; id c1 c2 2 test t ppc 9 abc ppc drop table t1, t2; create table t1 (i1 int auto_increment not null, i2 int, i3 int, primary key (i1)); create table t2 (id int auto_increment not null, c1 varchar(20), c2 varchar(20), primary key(id)); insert into t1 values (1,5,10),(3,7,12),(4,5,2),(9,10,15),(2,2,2); insert into t2 values (9,"abc","def"),(5,"opq","lmn"),(2,"test t","t test"); select * from t1 order by i1; i1 i2 i3 1 5 10 2 2 2 3 7 12 4 5 2 9 10 15 select * from t2 order by id; id c1 c2 2 test t t test 5 opq lmn 9 abc def update t1,t2 set t1.i2=15, t2.c2="ppc" where t1.i1=t2.id; select * from t1 order by i1; i1 i2 i3 1 5 10 2 15 2 3 7 12 4 5 2 9 15 15 select * from t2 order by id; id c1 c2 2 test t ppc 5 opq lmn 9 abc ppc delete t1.*,t2.* from t1,t2 where t1.i2=t2.id; select * from t1 order by i1; i1 i2 i3 2 15 2 3 7 12 9 15 15 select * from t2 order by id; id c1 c2 2 test t ppc 9 abc ppc drop table t1, t2; CREATE TABLE `t1` ( `a` int(11) NOT NULL auto_increment, `b` int(11) default NULL, PRIMARY KEY (`a`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 ; CREATE TABLE `t2` ( `a` int(11) NOT NULL auto_increment, `b` int(11) default NULL, PRIMARY KEY (`a`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 ; set @sav_binlog_format= @@session.binlog_format; set @@session.binlog_format= mixed; insert into t1 values (1,1),(2,2); insert into t2 values (1,1),(4,4); reset master; UPDATE t2,t1 SET t2.a=t1.a+2; ERROR 23000: Duplicate entry '3' for key 'PRIMARY' select * from t2 /* must be (3,1), (4,4) */; a b 3 1 4 4 show master status /* there must be the UPDATE query event */; File Position Binlog_Do_DB Binlog_Ignore_DB master-bin.000001 197 delete from t1; delete from t2; insert into t1 values (1,2),(3,4),(4,4); insert into t2 values (1,2),(3,4),(4,4); reset master; UPDATE t2,t1 SET t2.a=t2.b where t2.a=t1.a; ERROR 23000: Duplicate entry '4' for key 'PRIMARY' show master status /* there must be the UPDATE query event */; File Position Binlog_Do_DB Binlog_Ignore_DB master-bin.000001 212 drop table t1, t2; set @@session.binlog_format= @sav_binlog_format; drop table if exists t1, t2, t3; CREATE TABLE t1 (a int, PRIMARY KEY (a)); CREATE TABLE t2 (a int, PRIMARY KEY (a)); CREATE TABLE t3 (a int, PRIMARY KEY (a)) ENGINE=MyISAM; create trigger trg_del_t3 before delete on t3 for each row insert into t1 values (1); insert into t2 values (1),(2); insert into t3 values (1),(2); reset master; delete t3.* from t2,t3 where t2.a=t3.a; ERROR 23000: Duplicate entry '1' for key 'PRIMARY' select count(*) from t1 /* must be 1 */; count(*) 1 select count(*) from t3 /* must be 1 */; count(*) 1 drop table t1, t2, t3; end of tests