mysql> create table person_list
-> (
-> id int auto_increment unique,
-> name varchar(15) not null,
-> sex varchar(15) default "中",
-> ID_C varchar(20) not null unique,
-> vocation varchar(8),
-> salary float default 0.0
-> )charset=utf8;
Query OK, 0 rows affected (0.09 sec)
mysql> desc person_list;
+----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(15) | NO | | NULL | |
| sex | varchar(15) | YES | | 中 | |
| ID_C | varchar(20) | NO | UNI | NULL | |
| vocation | varchar(8) | YES | | NULL | |
| salary | float | YES | | 0 | |
+----------+-------------+------+-----+---------+----------------+
6 rows in set (0.00 sec)
mysql>
之后我往这张表里面添加了一些数据，从中可以看出我所说的问题mysql> select * from person_list; +----+-----------+------+--------------------+--------------+---------+ | id | name | sex | ID_C | vocation | salary | +----+-----------+------+--------------------+--------------+---------+ | 1 | 诸葛亮 | 男 | 360428199908230544 | 蜀国 | 8654.56 | | 2 | 关羽 | 男 | 360428198908230544 | 蜀国 | 86.236 | | 3 | 貂蝉 | 女 | 361428198908231479 | 美女集团 | 4566.02 | | 4 | 西施 | 女 | 795410365478901234 | 美女集团 | 124.1 | | 5 | 雷军 | 男 | 469787036544025984 | 小米公司 | 1784.1 | | 6 | 乔布斯 | 男 | 456982103749651024 | 苹果公司 | 88888.9 | | 7 | 李白 | 中 | 147852036978410210 | NULL | 0 | | 10 | 乔布儿 | 男 | 456902103749651024 | 苹果公司 | 88888.9 | | 13 | 乔布儿 | 男 | 056902103749651024 | 苹果公司 | 88888.9 | +----+-----------+------+--------------------+--------------+---------+ 9 rows in set (0.00 sec) mysql>如果我现在再插入一条记录，那么这个新增加的记录的"id"值会是14
mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
Query OK, 1 row affected (0.05 sec)
mysql> select * from person_list;
+----+-----------+------+--------------------+--------------+---------+
| id | name | sex | ID_C | vocation | salary |
+----+-----------+------+--------------------+--------------+---------+
| 1 | 诸葛亮 | 男 | 360428199908230544 | 蜀国 | 8654.56 |
| 2 | 关羽 | 男 | 360428198908230544 | 蜀国 | 86.236 |
| 3 | 貂蝉 | 女 | 361428198908231479 | 美女集团 | 4566.02 |
| 4 | 西施 | 女 | 795410365478901234 | 美女集团 | 124.1 |
| 5 | 雷军 | 男 | 469787036544025984 | 小米公司 | 1784.1 |
| 6 | 乔布斯 | 男 | 456982103749651024 | 苹果公司 | 88888.9 |
| 7 | 李白 | 中 | 147852036978410210 | NULL | 0 |
| 10 | 乔布儿 | 男 | 456902103749651024 | 苹果公司 | 88888.9 |
| 13 | 乔布儿 | 男 | 056902103749651024 | 苹果公司 | 88888.9 |
| 14 | 马云 | 男 | 444989898784562304 | 淘宝公司 | 54588.9 |
+----+-----------+------+--------------------+--------------+---------+
10 rows in set (0.00 sec)
mysql> 然后我故意输入10条错误的语句（这个表的ID_C值不能重复）mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
ERROR 1062 (23000): Duplicate entry '444989898784562304' for key 'ID_C'
mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
ERROR 1062 (23000): Duplicate entry '444989898784562304' for key 'ID_C'
mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
ERROR 1062 (23000): Duplicate entry '444989898784562304' for key 'ID_C'
mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
ERROR 1062 (23000): Duplicate entry '444989898784562304' for key 'ID_C'
mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
ERROR 1062 (23000): Duplicate entry '444989898784562304' for key 'ID_C'
mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
ERROR 1062 (23000): Duplicate entry '444989898784562304' for key 'ID_C'
mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
ERROR 1062 (23000): Duplicate entry '444989898784562304' for key 'ID_C'
mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
ERROR 1062 (23000): Duplicate entry '444989898784562304' for key 'ID_C'
mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
ERROR 1062 (23000): Duplicate entry '444989898784562304' for key 'ID_C'
mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云","男","444989898784562304","淘宝公司",54588.85124);
ERROR 1062 (23000): Duplicate entry '444989898784562304' for key 'ID_C'之后我又增加1条正确的记录，结果发现该新记录的"ID"值是25，最后一条
跟 倒数第二条 的"ID"值刚好是11-1=10mysql> insert into person_list (name,sex,ID_C,vocation,salary) value ("马云的儿子","男","444989898784562305","淘宝公司",54588.85124);
Query OK, 1 row affected (0.04 sec)
mysql> select * from person_list;
+----+-----------------+------+--------------------+--------------+---------+
| id | name | sex | ID_C | vocation | salary |
+----+-----------------+------+--------------------+--------------+---------+
| 1 | 诸葛亮 | 男 | 360428199908230544 | 蜀国 | 8654.56 |
| 2 | 关羽 | 男 | 360428198908230544 | 蜀国 | 86.236 |
| 3 | 貂蝉 | 女 | 361428198908231479 | 美女集团 | 4566.02 |
| 4 | 西施 | 女 | 795410365478901234 | 美女集团 | 124.1 |
| 5 | 雷军 | 男 | 469787036544025984 | 小米公司 | 1784.1 |
| 6 | 乔布斯 | 男 | 456982103749651024 | 苹果公司 | 88888.9 |
| 7 | 李白 | 中 | 147852036978410210 | NULL | 0 |
| 10 | 乔布儿 | 男 | 456902103749651024 | 苹果公司 | 88888.9 |
| 13 | 乔布儿 | 男 | 056902103749651024 | 苹果公司 | 88888.9 |
| 14 | 马云 | 男 | 444989898784562304 | 淘宝公司 | 54588.9 |
| 25 | 马云的儿子 | 男 | 444989898784562305 | 淘宝公司 | 54588.9 |
+----+-----------------+------+--------------------+--------------+---------+
11 rows in set (0.00 sec)
mysql> 所以我估摸着，在插入记录 语句错误的时候 自动增长类型的值会依旧增加，不是只有正确的时候才会+1。原文地址：http://blog.csdn.net/li_jun_09_05/article/details/45700407
