结论:当表的主键字段不是自增的时候,添加一条数据返回的最后插入字段的id的值就是0,但并不表示其插入错误或没有插入成功

上代码:

mysql> insert into hello(id, age) value (12,8);Query OK, 1 row affected (0.00 sec)mysql> select last_insert_id();+------------------+| last_insert_id() |+------------------+|                0 |+------------------+1 row in set (0.00 sec)mysql> desc hello;+-------+---------+------+-----+---------+-------+| Field | Type    | Null | Key | Default | Extra |+-------+---------+------+-----+---------+-------+| id    | int(11) | NO   | PRI | NULL    |       || age   | int(11) | YES  |     | NULL    |       |+-------+---------+------+-----+---------+-------+2 rows in set (0.01 sec)mysql> select * from hello;+----+------+| id | age  |+----+------+|  1 | NULL ||  2 | NULL ||  5 |    0 ||  6 | NULL ||  9 |    1 || 10 |    2 || 11 |    8 || 12 |    8 |+----+------+8 rows in set (0.00 sec)