Mysql聚合函数。平均价格和商品价格

Question

我想知道有多少商品价格高于平均价格且价格较低。

我的查询：

SELECT COUNT(*)
FROM item i
WHERE refine = 0 AND item = 5170
GROUP BY id
HAVING price > AVG(price) - STD(price) AND i.price < AVG(price) + STD(price)

但我在'having clause'

中收到错误未知栏'价格'

如果我在SELECT中使用AVG和STD函数：

SELECT COUNT(*), SUM(price > AVG(price) - STD(price) AND i.price < AVG(price) + STD(price)) as middle
FROM item i
WHERE refine = 0 AND item = 5170

我再次收到错误。如何进行正确的查询？

此处链接sqlFiddle

Answer 1

试试这个

select count(*) from item as t1 inner join
(
select id,AVG(price) - STD(price) as sum1, AVG(price) + STD(price)  as sum2
from item 
group by id
) as t2
on t1.id=t2.id and t1.price>sum1 and t1.price<sum2

Answer 2

SELECT COUNT(*), SUM(price > AVG(price)) - STD(price) AND i.price < AVG(price) + STD(price)) as    middle
 FROM item i WHERE refine = 0 AND item = 5170

你忘了“）” - ＆gt; SUM(price > AVG(price))