前言
近期多次聊到sql_mode的話題，也是多次遇到相關問題，今天就趁熱打鐵，再給大家帶來一個sql_mode的案例分享。
場景模擬
基于業務敏感性的考慮，下面涉及的表、存儲過程等均非真實數據，但并不影響排查過程。
（1）客戶側開發童鞋創建了一個存儲過程，該存儲過程沒有嚴格遵守group by標準語法
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）客戶側開發童鞋調用該存儲過程，報錯ERROR 1140；因為當時存儲過程比較復雜，改造起來比較麻煩，所以客戶側選擇修改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）客戶側修改完sql_mode，再次執行，發現仍然報錯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）此時想到，修改系統變量，只對新建連接有效，對已有連接不起作用；于是，讓客戶側重新建立連接，確認系統變量已生效，再次調用存儲過程，但仍然報錯ERROR 1140，重復嘗試幾次都是這個結果
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）進一步排查，讓客戶側在該會話，執行非標準的group by語句，發現可以正常執行
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）繼續排查發現，該存儲過程的sql_mode，還是包括ONLY_FULL_GROUP_BY，因此執行報錯
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）這里我們也可以知道，系統變量修改只對新建對象有效，對已有對象不生效；解決辦法很簡單，重建該存儲過程即可
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)
總結
通過這個案例，我們可以知道，修改sql_mode系統變量，只對新建連接和新建對象(主要包括函數和存儲過程)有效，對已有連接和已有對象不生效。
以上就是MySQL sql_mode修改不生效的原因及解決的詳細內容，更多關于MySQL sql_mode修改不生效的資料請關注腳本之家其它相關文章！
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