Mysql聚合函數。平均價格和物品價格

Question

想要在一個查詢中獲得多少物品的價格高於平均價格和更低。

我的查詢：

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) 

，但我得到的錯誤未知列'價格 'having子句'

中如果我使用AVG和STD功能選擇：

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 

我再次收到錯誤消息。如何進行正確的查詢？

這裏就sqlFiddle

Answer 1

試試這個

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 「）」 鏈接 - >SUM(price > AVG(price))