increment是干什么的？

自增列

例子如下:

mysql> CREATE TABLE test_create_tab2 (

-> id INT AUTO_INCREMENT,

-> val VARCHAR(10),

-> PRIMARY KEY (id)

-> );

Query OK, 0 rows affected (0.09 sec)

mysql> INSERT INTO test_create_tab2(val) VALUES ('NO id');

Query OK, 1 row affected (0.03 sec)

mysql> select last_insert_id() as id;

+----+

id

+----+

1

+----+

1 row in set (0.00 sec)

mysql> INSERT INTO test_create_tab2(val) VALUES ('NO id 2');

Query OK, 1 row affected (0.03 sec)

mysql> select last_insert_id() as id;

+----+

id

+----+

2

+----+

1 row in set (0.00 sec)

mysql> select * from test_create_tab2;

+----+---------+

id | val

+----+---------+

1 | NO id

2 | NO id 2

+----+---------+

2 rows in set (0.00 sec)