MySQL：1055错误

（Error Code: 1055. Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'school.b.s_name' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by）

错误原因：在MySQL5.7之后，sql_mode中默认存在ONLY_FULL_GROUP_BY，SQL语句未通过ONLY_FULL_GROUP_BY语义检查所以报错。

ONLY_FULL_GROUP_BY：ONLY_FULL_GROUP_BY要求select语句中查询出来的列必须是明确的（其他语句也是一样）。

解决办法：

在当前服务中临时解决MySQL8.0 1055错误

执行语句：set sql_mode ='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION';

（永久解决需要在配置文件中更改，可参考：https://www.cnblogs.com/haoyul/p/9882853.html）