前言：
今天姐妹们对“mysql中的检查约束”可能比较关怀，各位老铁们都想要分析一些“mysql中的检查约束”的相关文章。那么小编也在网上汇集了一些对于“mysql中的检查约束””的相关内容，希望大家能喜欢，同学们快快来学习一下吧！比如：sztech下面的一张表emp,查它有几个约束 ：
mysql> use sztech
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> show create table emp\G
*************************** 1. row ***************************
Table: emp
Create Table: CREATE TABLE `emp` (
`empid` int(11) NOT NULL DEFAULT '0',
`last_name` varchar(20) DEFAULT NULL,
`salary` double DEFAULT NULL,
`hire_date` date DEFAULT NULL,
PRIMARY KEY (`empid`),
KEY `idx_emp_empid` (`empid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)
mysql> alter table emp add primary key (empid);
mysql> select CONSTRAINT_SCHEMA, CONSTRAINT_NAME,TABLE_NAME,CONSTRAINT_TYPE from information_schema.TABLE_CONSTRAINTS where TABLE_NAME='emp';
+-------------------+-----------------+------------+-----------------+
| CONSTRAINT_SCHEMA | CONSTRAINT_NAME | TABLE_NAME | CONSTRAINT_TYPE |
+-------------------+-----------------+------------+-----------------+
| sztech | PRIMARY | emp | PRIMARY KEY |
+-------------------+-----------------+------------+-----------------+
1 row in set (0.00 sec)
标签： #mysql中的检查约束
