说明
1、auto_increment约束条件就是加在主键字段上的,并且在插入数据的时候主键的值无需手动插入了。
2、auto_increment数据列必须有唯一索引,以避免序号重复。必须具备NOT NULL属性。
实例
-- 创建表的完整语法 mysql> create table t5(id int primary key auto_increment, name varchar(4), age int(3), phone varchar(11)); Query OK, 0 rows affected (0.01 sec) mysql> insert into t5 (name, age, phone) values ('python', 5, '119'),('java', 10, '120'); Query OK, 2 rows affected, 1 warning (0.15 sec) Records: 2 Duplicates: 0 Warnings: 1 mysql> select * from t5; +----+------+------+-------+ | id | name | age | phone | +----+------+------+-------+ | 1 | pyth | 5 | 119 | | 2 | java | 10 | 120 | +----+------+------+-------+ 2 rows in set (0.00 sec) mysql> desc t5; +-------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | varchar(4) | YES | | NULL | | | age | int(3) | YES | | NULL | | | phone | varchar(11) | YES | | NULL | | +-------+-------------+------+-----+---------+----------------+ 4 rows in set (0.01 sec)
以上就是mysql中auto_increment的介绍,希望对大家有所帮助。更多mysql学习指路:MySQL
推荐操作系统:windows7系统、mysql5.8、DELL G3电脑