报错如下：
Error Code: 1055. Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'basic_exercise.stu.Sname' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by
- step 1 :查询mysql 相关mode
select @@global.sql_mode;
select @@session.sql_mode;
- steo 2: 重设模式值
去掉ONLY_FULL_GROUP_BY即可
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';
SET @@session.sql_mode ='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO'
MySQL 5.7.5及以上功能依赖检测功能。如果启用了ONLY_FULL_GROUP_BY SQL模式（默认情况下），MySQL将拒绝选择列表，HAVING条件或ORDER BY列表的查询引用在GROUP BY子句中既未命名的非集合列，也不在功能上依赖于它们。（5.7.5之前，MySQL没有检测到功能依赖关系，默认情况下不启用ONLY_FULL_GROUP_BY。有关5.7.5之前的行为的说明，请参见“MySQL 5.6参考手册”。）
