MYSQL使用GROUP BY 时报错only_full_group_by的解决方法

我在输入SQL语句 

 SELECT grade FROM sy_epwk GROUP BY grade='一品';

时mysql报错：ERROR 1055 (42000): Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'pro_data.sy_epwk.grade' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

各种百度寻找解决方法，了解到使用group by select中要有聚合函数，并且所有非聚合函数的列都要现现在group by 后

可是我是个新手，理解不了这句话的含义。试过百度上的设置sql_mode，可是设置了很久都报错。于是自己查看官方文档

 

 

先在mysql客户端输入show variables like 'sql_mode';查看当前的sql_mode：

 

我发现只要把开头的ONLY_FULL_GROUP_BY去掉就可以了

于是输入 set sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';

 

最后再运行SELECT grade FROM sy_epwk GROUP BY grade='一品';

执行成功