Mysql聚合函数。平均价格和物品价格

Question

想要在一个查询中获得多少物品的价格高于平均价格和更低。

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) 

，但我得到的错误未知列'价格 'having子句'

中如果我使用AVG和STD功能选择：

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 

我再次收到错误消息。如何进行正确的查询？

这里就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 “）” 链接 - >SUM(price > AVG(price))