含义where在分组之前就进行选择操作havinghaving在分组操作之后才进行选择操作,所以having可以选择聚合函数eg:// 下面这句是可以的SELECT COUNT(*) FROM AWHERE A.a1>0GROUP BY a2;//但是下面就不行SELECT COUNT(*) FROM AWHERE A.a1>0 and coun..
看代码:复制代码 代码如下:set statistics io on set statistics time on go set statistics profile on go use pubs select * from authors where (au_fname like 'S%' or au_fname like 'a%') and (state like 'CA' or state like 'UT') and (ca..
1.where 不能放在GROUP BY 后面2.HAVING 是跟GROUP BY 连在一起用的,放在GROUP BY 后面,此时的作用相当于WHERE3.WHERE 后面的条件中不能有聚集函数,比如SUM(),AVG()等,而HAVING 可以Where和Having都是对查询结果的一种筛选,说的书面点就是设定..