mysql基础——简单分组查询07
分组查询group by
select cno, (count(*)) from product group by cno;
select cno ,avg(price) from product group by cno having avg(price) > 60;
having 可以接聚合函数,出现在分组后
where 它是不可以接聚合函数,出现在分组前
select cno, (count(*)) from product group by cno;
select cno ,avg(price) from product group by cno having avg(price) > 60;
having 可以接聚合函数,出现在分组后
where 它是不可以接聚合函数,出现在分组前