ORDER BY 子句中的列必须包含在聚合函数或 GROUP BY 子句中。
slect * from table group by class,id order by id
slect * from table group by class,id order by class
ORDER BY 子句中的列必须包含在聚合函数或 GROUP BY 子句中。
slect * from table group by class,id order by id
slect * from table group by class,id order by class