MySQL sql_mode修改不生效的原因及解决

本篇文章主要是结合我之前面试的各种经历和实战开发中遇到的问题解决经验整理的，希望这篇《MySQL sql_mode修改不生效的原因及解决》对你有很大帮助！欢迎收藏，分享给更多的需要的朋友学习~

前言

近期多次聊到sql_mode的话题，也是多次遇到相关问题，今天就趁热打铁，再给大家带来一个sql_mode的案例分享。

场景模拟

基于业务敏感性的考虑，下面涉及的表、存储过程等均非真实数据，但并不影响排查过程。

（1）客户侧开发童鞋创建了一个存储过程，该存储过程没有严格遵守group by标准语法

session 1：
mysql> delimiter //

mysql> create procedure test_for_group_by()
    -> begin
    -> select k,pad,count(*) from test.test group by k;
    -> end //
Query OK, 0 rows affected (0.01 sec)

mysql> delimiter ;

（2）客户侧开发童鞋调用该存储过程，报错ERROR 1140；因为当时存储过程比较复杂，改造起来比较麻烦，所以客户侧选择修改sql_mode

session 1：
mysql> call test_for_group_by();
ERROR 1140 (42000): In aggregated query without GROUP BY, expression #1 of SELECT list contains nonaggregated column 'test.test.k'; this is incompatible with sql_mode=only_full_group_by

（3）客户侧修改完sql_mode，再次执行，发现仍然报错ERROR 1140

session 2：
mysql> set global sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
Query OK, 0 rows affected (0.00 sec)

session 1：
mysql> call test_for_group_by();
ERROR 1140 (42000): In aggregated query without GROUP BY, expression #1 of SELECT list contains nonaggregated column 'test.test.k'; this is incompatible with sql_mode=only_full_group_by

（4）此时想到，修改系统变量，只对新建连接有效，对已有连接不起作用；于是，让客户侧重新建立连接，确认系统变量已生效，再次调用存储过程，但仍然报错ERROR 1140，重复尝试几次都是这个结果

session 3：
mysql> show variables like 'sql_mode';
+---------------+------------------------------------------------------------------------------------------------------------------------+
| Variable_name | Value                                                                                                                  |
+---------------+------------------------------------------------------------------------------------------------------------------------+
| sql_mode      | STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+---------------+------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)

mysql> call test_for_group_by();
ERROR 1140 (42000): In aggregated query without GROUP BY, expression #1 of SELECT list contains nonaggregated column 'test.test.k'; this is incompatible with sql_mode=only_full_group_by

（5）进一步排查，让客户侧在该会话，执行非标准的group by语句，发现可以正常执行

session 3：
mysql> select user,host,count(*) From mysql.user group by user;
+---------------+-----------+----------+
| user          | host      | count(*) |
+---------------+-----------+----------+
| mysql.session | localhost |        1 |
| mysql.sys     | localhost |        1 |
| root          | localhost |        1 |
| rpl_user      | %         |        1 |
| test          | %         |        1 |
+---------------+-----------+----------+
5 rows in set (0.00 sec)

（6）继续排查发现，该存储过程的sql_mode，还是包括ONLY_FULL_GROUP_BY，因此执行报错

session 2：
mysql> select routine_catalog,routine_schema,routine_name,routine_type,created,last_altered,sql_mode from routines where routine_name='test_for_group_by';
+-----------------+----------------+-------------------+--------------+---------------------+---------------------+-------------------------------------------------------------------------------------------------------------------------------------------+
| routine_catalog | routine_schema | routine_name      | routine_type | created             | last_altered        | sql_mode                                                                                                                                  |
+-----------------+----------------+-------------------+--------------+---------------------+---------------------+-------------------------------------------------------------------------------------------------------------------------------------------+
| def             | test           | test_for_group_by | PROCEDURE    | 2020-12-24 12:12:10 | 2020-12-24 12:12:10 | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+-----------------+----------------+-------------------+--------------+---------------------+---------------------+-------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

（7）这里我们也可以知道，系统变量修改只对新建对象有效，对已有对象不生效；解决办法很简单，重建该存储过程即可

session 3：
mysql> drop procedure test_for_group_by;
Query OK, 0 rows affected (0.01 sec)

mysql> delimiter //

mysql> create procedure test_for_group_by()
    -> begin
    -> select k,pad,count(*) from test.test group by k;
    -> end //
Query OK, 0 rows affected (0.01 sec)

mysql> delimiter ;

mysql> call test_for_group_by();
+--------+-------------------------------------------------------------+----------+
| k      | pad                                                         | count(*) |
+--------+-------------------------------------------------------------+----------+
| 393975 | 35227182905-15234265621-59793845249-15413569710-23749555118 |        1 |
| 495688 | 09512147864-77936258834-40901700703-13541171421-15205431759 |        1 |
| 497896 | 13152283289-69561545685-52868757241-04245213425-69280254356 |        1 |
| 498573 | 43131080328-59298106536-35954612339-97546855884-75769514803 |        1 |
| 500775 | 27590239742-20204899609-34345212327-79811525340-24267764271 |        1 |
| 501885 | 63188288836-92351140030-06390587585-66802097351-49282961843 |        1 |
| 503330 | 01495266405-82925129145-92643983850-90243995398-18709399387 |        1 |
| 503666 | 40929980986-33813039690-13155419391-97985458477-39771362212 |        1 |
| 504353 | 00505722282-72931248925-57037623248-81117963809-88658076981 |        1 |
| 514246 | 21979564480-87492594656-60524686334-78820761788-57684966682 |        1 |
+--------+-------------------------------------------------------------+----------+
10 rows in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

总结

通过这个案例，我们可以知道，修改sql_mode系统变量，只对新建连接和新建对象(主要包括函数和存储过程)有效，对已有连接和已有对象不生效。

好了，本文到此结束，带大家了解了《MySQL sql_mode修改不生效的原因及解决》，希望本文对你有所帮助！关注golang学习网公众号，给大家分享更多数据库知识！