sql_mode
mysql> select @@sql_mode; +------------------------------------------------------------------------------------------------------------------------+ | @@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 (0.00 sec) mysql> select distinct empno from EMP order by deptno ; +-------+ | empno | +-------+ | 1 | | 0 | +-------+ 2 rows in set (0.02 sec) mysql> set sql_mode ='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'; Query OK, 0 rows affected (0.01 sec) mysql> select distinct empno from EMP order by deptno ; ERROR 3065 (HY000): Expression #1 of ORDER BY clause is not in SELECT list, references column 'test.EMP.DEPTNO' which is not in SELECT list; this is incompatible with DISTINCT mysql>
5.6之前默认非严格的分组函数，5.7开始默认是严格的聚合函数，通过ONLY_FULL_GROUP_BY控制
