mysql中的sql_mode模式实例详解

本文实例讲述了mysql中的sql_mode模式。分享给大家供大家参考，具体如下：

mysql数据库的中有一个环境变量sql_mode,定义了mysql应该支持的sql语法，数据校验等！我们可以通过以下方式查看当前数据库使用的sql_mode：

mysql> select @@sql_mode;+----------------------------------------------------------------+| @@sql_mode                           |+----------------------------------------------------------------+| STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |+----------------------------------------------------------------+

ANSI模式

宽松模式，对插入数据进行校验，如果不符合定义类型或长度，对数据类型调整或截断保存，报warning警告。

TRADITIONAL模式

严格模式，当向mysql数据库插入数据时，进行数据的严格校验，保证错误数据不能插入，报error错误。用于事物时，会进行事物的回滚。

STRICT_TRANS_TABLES模式

严格模式，进行数据的严格校验，错误数据不能插入，报error错误。

1 ANSI模式

在ANSI模式下，当我们插入数据时，未满足列长度要求时，数据同样会插入成功，但是对超出列长度的字段进行截断，同时报告warning警告。

mysql> set @@sql_mode=ANSI;Query OK, 0 rows affected (0.00 sec)mysql> create table test(name varchar(4), pass varchar(4));Query OK, 0 rows affected (0.03 sec)mysql> insert into test values('aaaaa','aaaaa'),('bbbb','bbbb');Query OK, 2 rows affected, 2 warnings (0.02 sec)Records: 2 Duplicates: 0 Warnings: 2mysql> show warnings;+---------+------+-------------------------------------------+| Level  | Code | Message                  |+---------+------+-------------------------------------------+| Warning | 1265 | Data truncated for column 'name' at row 1 || Warning | 1265 | Data truncated for column 'pass' at row 1 |+---------+------+-------------------------------------------+2 rows in set (0.00 sec)mysql> select * from test;+------+------+| name | pass |+------+------+| aaaa | aaaa || bbbb | bbbb |+------+------+2 rows in set (0.00 sec)

在STRICT_TRANS_TABLES模式下，当我们插入数据时，mysql会严格的进行数据的校验，当发现插入列值未满足要求，直接报告error错误，保证了错误数据无法插入到数据库中。

mysql> set @@sql_mode=STRICT_TRANS_TABLES;Query OK, 0 rows affected (0.00 sec)mysql> create table test(name varchar(4), pass varchar(4));Query OK, 0 rows affected (0.02 sec)mysql> insert into test values('aaaaa','aaaaa'),('bbbb','bbbb');ERROR 1406 (22001): Data too long for column 'name' at row 1mysql> show errors;+-------+------+------------------------------------------+| Level | Code | Message                 |+-------+------+------------------------------------------+| Error | 1406 | Data too long for column 'name' at row 1 |+-------+------+------------------------------------------+1 row in set (0.00 sec)mysql> select * from test;Empty set (0.00 sec)

mysql> set @@sql_mode=TRADITIONAL;Query OK, 0 rows affected (0.00 sec)mysql> create table test(name varchar(4), pass varchar(4));Query OK, 0 rows affected (0.02 sec)mysql> insert into test values('aaaaa','aaaaa'),('bbbb','bbbb');ERROR 1406 (22001): Data too long for column 'name' at row 1mysql> show errors;+-------+------+------------------------------------------+| Level | Code | Message                 |+-------+------+------------------------------------------+| Error | 1406 | Data too long for column 'name' at row 1 |+-------+------+------------------------------------------+1 row in set (0.00 sec)mysql> select * from test;Empty set (0.00 sec)

mysql> set @@sql_mode=TRADITIONAL;Query OK, 0 rows affected (0.00 sec)mysql> select @@sql_mode\G*************************** 1. row ***************************@@sql_mode: STRICT_TRANS_TABLES,STRICT_ALL_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,TRADITIONAL,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION1 row in set (0.00 sec)

最后：

set @@只是在sessions级别设置的，要想所有的都生效，还是要设置配置文件

vi /etc/my.cnf

在[mysqld]下面添加如下列：

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES

另外：sql_mode还有一个配置ONLY_FULL_GROUP_BY，这个表示采用group by帅选数据的时候只能查看新组内信息

改模式之前的操作

mysql> select * from employee group by post;+----+--------+--------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+| id | name  | sex  | age | hire_date | post                  | post_comment | salary   | office | depart_id |+----+--------+--------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+| 14 | 张野  | male  | 28 | 2016-03-11 | operation                | NULL     |  10000.13 |  403 |     3 || 9 | 歪歪  | female | 48 | 2015-03-11 | sale                  | NULL     |  3000.13 |  402 |     2 || 2 | alex  | male  | 78 | 2015-03-02 | teacher                 | NULL     | 1000000.31 |  401 |     1 || 1 | egon  | male  | 18 | 2017-03-01 | 老男孩驻沙河办事处外交大使       | NULL     |  7300.33 |  401 |     1 |+----+--------+--------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+4 rows in set (0.00 sec)

mysql> select @@sql_mode;+----------------------------------------------------------------+| @@sql_mode                           |+----------------------------------------------------------------+| STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |+----------------------------------------------------------------+1 row in set (0.00 sec)

mysql> set global sql_mode='STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION,ONLY_FULL_GROUP_BY';Query OK, 0 rows affected (0.00 sec)mysql> select @@sql_mode;+----------------------------------------------------------------+| @@sql_mode                           |+----------------------------------------------------------------+| STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |+----------------------------------------------------------------+1 row in set (0.00 sec)mysql> exitBye

mysql> select @@sql_mode;+-----------------------------------------------------------------------------------+| @@sql_mode |+-----------------------------------------------------------------------------------+| ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |+-----------------------------------------------------------------------------------+1 row in set (0.00 sec)

mysql> select * from employee group by post;  //只能查看postERROR 1055 (42000): 't1.employee.id' isn't in GROUP BYmysql> select post from employee group by post;+-----------------------------------------+| post                  |+-----------------------------------------+| operation                || sale                  || teacher                 || 老男孩驻沙河办事处外交大使       |+-----------------------------------------+4 rows in set (0.00 sec)mysql> select id,post from employee group by post;ERROR 1055 (42000): 't1.employee.id' isn't in GROUP BYmysql> select name,post from employee group by post,name; //根据group by 后面的选择查看+------------+-----------------------------------------+| name | post |+------------+-----------------------------------------+| 张野 | operation || 程咬金 | operation || 程咬铁 | operation || 程咬铜 | operation || 程咬银 | operation || 丁丁 | sale || 丫丫 | sale || 星星 | sale || 格格 | sale || 歪歪 | sale || alex | teacher || jingliyang | teacher || jinxin | teacher || liwenzhou | teacher || wupeiqi | teacher || xiaomage | teacher || yuanhao | teacher || egon | 老男孩驻沙河办事处外交大使 |+------------+-----------------------------------------+18 rows in set (0.00 sec)

希望本文所述对大家MySQL数据库计有所帮助。

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