关于Mysql中 select last_insert_id() 取值问题

mysql中可以设置主键自增:

mysql> create table t1(id int primary key auto_increment,name varchar(20));
Query OK, 0 rows affected (0.00 sec)

mysql> desc t1;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(20) | YES  |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)


mysql> create table t2(id int primary key auto_increment,name varchar(20));
Query OK, 0 rows affected (0.00 sec)

mysql> desc t2;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(20) | YES  |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)mysql> create table t1(id