例如,我想使字段 id 自增。
1、查看表定义
mysql> DESC user;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id | int(8) | NO | PRI | NULL | |
| account | varchar(16) | YES | | NULL | |
| password | varchar(16) | YES | | NULL | |
+----------+-------------+------+-----+---------+-------+
2、更改表结构
mysql> ALTER TABLE user CHANGE COLUMN id id INT(8) NOT NULL AUTO_INCREMENT;
3、重新查看表定义
mysql> DESC user;
+----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+----------------+
| id | int(8) | NO | PRI | NULL | auto_increment |
| account | varchar(16) | YES | | NULL | |
| password | varchar(16) | YES | | NULL | |
+----------+-------------+------+-----+---------+----------------+