SQL子查詢問題

Question

我的問題是檢索出售每個商品的商店數量超過平均市場價格;

SELECT SHOP_NAME, Trade_Name 
FROM SELL_ITEM f 
WHERE PRICE > 
    (SELECT 
    AVG(PRICE) 
    FROM SELL_ITEM s 
    WHERE f.Trade_Name = s.Trade_Name 
    GROUP BY TRADE_NAME); 

該查詢返回我所有的商店，出售項目>高於市場平均價格，但我怎麼能過濾掉那些不是爲每個項目？

Answer 1

編輯...（錯過了一個細微的第一次）

SELECT shop_name FROM 
(
    SELECT shop_name, MIN(case when f.price > a.avg_price then 1 else 0 end) AS is_always_higher_than_avg 
    FROM SELL_ITEM f 
    INNER JOIN 
    (
     SELECT avg(price) AS avg_price, trade_name 
     FROM sell_item 
     GROUP BY trade_name 
    ) a 
    ON f.trade_name = a.trade_name 
    WHERE f.price > a.avg_price 
    GROUP BY shop_name 
) b 
WHERE is_always_higher_than_avg = 1