group by 点滴

select pub ,sum(price) from books group by pub

select 前面有的 group by 后面一定要有
where sum(price)>10 错
聚集函数是不能作为where条件的
可以用having
select pub ,sum(price) from books group by pub having sum(price)>10;


聚合函数  不能再where条件

还有 selecte 要显示的列 后面 group 不要一定要有