当 LAST_INSERT_ID() 带有参数时# 清空重来

[[e-mail]]> truncate table t;

# 插入1条新记录

[[e-mail]]> insert into t select 0,rand()*1024;

# 查看 last_insert_id(), 符合预期

[[e-mail]]> select last_insert_id();

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

| last_insert_id() |

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

| 1 |

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

[[e-mail]]> select * from t;

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

| id | c1 |

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

| 1 | 730 |

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

# 调用 last_insert_id() 时增加表达式

[[e-mail]]> select last_insert_id(id+2) from t;

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

| last_insert_id(id+2) |

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

| 3 |

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

# 再看 last_insert_id() 的值，好像“又不符合预期”了

[[e-mail]]> select last_insert_id();

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

| last_insert_id() |

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

| 3 |

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

# 插入1条新纪录

[[e-mail]]> insert into t select 0,rand()*1024;

# 再看 last_insert_id() 的值，好像“又回到正轨”了

[[e-mail]]> select last_insert_id();

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

| last_insert_id(http://www.amjmh.com) |

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

| 2 |

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

[[e-mail]]> select * from t;

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

| id | c1 |

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

| 1 | 730 |

| 2 | 600 |

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

2 rows in set (0.00 sec)