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set @save_check_constraint=@@check_constraint_checks;
create table t1 (a int check(a>10), b int check (b > 20), constraint `min` check (a+b > 100), constraint `max` check (a+b <500)) engine=myisam;
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` int(11) DEFAULT NULL CHECK (a>10),
`b` int(11) DEFAULT NULL CHECK (b > 20),
CONSTRAINT `min` CHECK (a+b > 100),
CONSTRAINT `max` CHECK (a+b <500)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
insert into t1 values (100,100);
insert into t1 values (1,1);
ERROR HY000: CONSTRAINT 'a' failed for 'test.t1'
insert into t1 values (20,1);
ERROR HY000: CONSTRAINT 'b' failed for 'test.t1'
insert into t1 values (20,30);
ERROR HY000: CONSTRAINT 'min' failed for 'test.t1'
insert into t1 values (500,500);
ERROR HY000: CONSTRAINT 'max' failed for 'test.t1'
insert into t1 values (101,101),(102,102),(600,600),(103,103);
ERROR HY000: CONSTRAINT 'max' failed for 'test.t1'
select * from t1;
a b
100 100
101 101
102 102
truncate table t1;
insert ignore into t1 values (101,101),(102,102),(600,600),(103,103);
Warnings:
Warning 1369 CONSTRAINT 'max' failed for 'test.t1'
select * from t1;
a b
101 101
102 102
103 103
set check_constraint_checks=0;
truncate table t1;
insert into t1 values (101,101),(102,102),(600,600),(103,103);
select * from t1;
a b
101 101
102 102
600 600
103 103
set check_constraint_checks=@save_check_constraint;
alter table t1 add c int default 0 check (c < 10);
ERROR HY000: CONSTRAINT 'max' failed for table
set check_constraint_checks=0;
alter table t1 add c int default 0 check (c < 10);
alter table t1 add check (a+b+c < 500);
set check_constraint_checks=@save_check_constraint;
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` int(11) DEFAULT NULL CHECK (a>10),
`b` int(11) DEFAULT NULL CHECK (b > 20),
`c` int(11) DEFAULT '0' CHECK (c < 10),
CONSTRAINT `min` CHECK (a+b > 100),
CONSTRAINT `max` CHECK (a+b <500),
CONSTRAINT `CONSTRAINT_1` CHECK (a+b+c < 500)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
insert into t1 values(105,105,105);
ERROR HY000: CONSTRAINT 'c' failed for 'test.t1'
insert into t1 values(249,249,9);
ERROR HY000: CONSTRAINT 'CONSTRAINT_1' failed for 'test.t1'
insert into t1 values(105,105,9);
select * from t1;
a b c
101 101 0
102 102 0
600 600 0
103 103 0
105 105 9
create table t2 like t1;
show create table t2;
Table Create Table
t2 CREATE TABLE `t2` (
`a` int(11) DEFAULT NULL CHECK (a>10),
`b` int(11) DEFAULT NULL CHECK (b > 20),
`c` int(11) DEFAULT '0' CHECK (c < 10),
CONSTRAINT `min` CHECK (a+b > 100),
CONSTRAINT `max` CHECK (a+b <500),
CONSTRAINT `CONSTRAINT_1` CHECK (a+b+c < 500)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
alter table t2 drop constraint c;
ERROR 42000: Can't DROP 'c'; check that constraint/column/key exists
alter table t2 drop constraint min;
show create table t2;
Table Create Table
t2 CREATE TABLE `t2` (
`a` int(11) DEFAULT NULL CHECK (a>10),
`b` int(11) DEFAULT NULL CHECK (b > 20),
`c` int(11) DEFAULT '0' CHECK (c < 10),
CONSTRAINT `max` CHECK (a+b <500),
CONSTRAINT `CONSTRAINT_1` CHECK (a+b+c < 500)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1,t2;
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