按2个值之间的平均评分排序

Question

我有一个名为ranks的表，它存储1-7值并将其与项目和用户ID相关联。商品的评级是给出的所有评级的平均值。

排名表：id | userid | value | itemid.

按平均最高评分排序，我这样做（来自这里的答案）：

select avg(value), itemid
from ranks
group by itemid
order by avg(value) desc

但是，我还希望能够过滤具有特定评级的项目，而不仅仅是最高评级 - ＆gt;评分最低。例如，平均评分为5和6的项目。

select avg(value), itemid
from ranks
having avg(value) between 5 and 6
group by itemid
order by avg(value) desc

这给了我group by的非特定错误。有人能指出我正确的方向吗？

Answer 1

select * from
(
select avg(value) as avgval, itemid
from ranks
group by itemid) t
where avgval between 5 and 6;

您可以使用子查询来完成。

Answer 2

您的having条款需要在您的group by条款之后，所以只需颠倒它们出现的顺序：

select avg(value), itemid
from ranks
group by itemid
having avg(value) between 5 and 6
order by avg(value) desc

Answer 3

with Temp as 
(
select avg(value) [rating], itemid
from ranks
)
Select * from Temp
Where rating between 5 and 6
group by itemid
order by rating desc