1055 – Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column

MARK

1055 - Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'student.b.C_id' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by, Time: 0.002000s
nonaggregate 非聚集
出现这个情况的原因是我这个b.C_Id 不是可以分组的项，把它删掉即可。

1055 – Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column最先出现在Python成神之路。