mysql 给表添加唯一约束、联合唯一约束，指定唯一约束的名字

表结构

FIELD          TYPE          COLLATION       NULL    KEY     DEFAULT  Extra           PRIVILEGES            COMMENT
-------------  ------------  --------------  ------  ------  -------  --------------  --------------------  -------
id             BIGINT(20)    (NULL)          NO      PRI     (NULL)   AUTO_INCREMENT  SELECT,INSERT,UPDATE         
resource_name  VARCHAR(128)  gbk_chinese_ci  YES             (NULL)                   SELECT,INSERT,UPDATE         
resource_type  TINYINT(4)    (NULL)          YES             (NULL)                   SELECT,INSERT,UPDATE 

给resource_name和resource_type添加联合唯一约束

ALTER TABLE jw_resource
ADD UNIQUE KEY(resource_name, resource_type);

结果 show create table jw_resource;

CREATE TABLE `jw_resource` (
  `id` BIGINT(20) NOT NULL AUTO_INCREMENT,
  `resource_name` VARCHAR(128) DEFAULT NULL,
  `resource_type` TINYINT(4) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `resource_name` (`resource_name`,`resource_type`)
) ENGINE=INNODB AUTO_INCREMENT=2 DEFAULT CHARSET=gbk

删除唯一约束

ALTER TABLE jw_role DROP INDEX resource_name;

增加一个唯一约束，并且给唯一约束起名字？

原表结构：

mysql> show create table test_table;
+------------+--------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------+
| Table      | Create Table
                                 |
+------------+--------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------+
| test_table | CREATE TABLE `test_table` (
  `id` int(50) NOT NULL AUTO_INCREMENT,
  `kk` varchar(30) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=latin1 |
+------------+--------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------+
1 row in set (0.00 sec)

增加唯一约束的语句，给唯一约束起名叫做 kk_uq：

mysql> alter table test_table add unique key `kk_uq` ( kk);

查看结果

mysql> show create table test_table;
+------------+--------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------+
| Table      | Create Table
                                                              |
+------------+--------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------+
| test_table | CREATE TABLE `test_table` (
  `id` int(50) NOT NULL AUTO_INCREMENT,
  `kk` varchar(30) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `kk_uq` (`kk`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=latin1 |
+------------+--------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------+
1 row in set (0.00 sec)