使用group by和having子句的MySQL查詢

Question

我正在構造查詢以獲取相同產品的最高價格。 我有桌子

-----------------------------------------
|   prod_id  |   price   |    user_id   |
-----------------------------------------
|     4      |   25      |       1      |
|     4      |   38      |       2      |
|     4      |   41      |       3      |
|     7      |   100     |       1      |
|     7      |   95      |       2      |
-----------------------------------------

我正在嘗試獲得以下輸出：

-----------------------------------------
|     4      |   41      |       3      |
-----------------------------------------
|     7      |   100     |       1      |
-----------------------------------------

我構造了以下查詢，這是不正確的。

select * from user_bid group by prod_id having max(price);

有人可以指導我獲取所需結果的查詢。

Answer 1

這是使用聯接的選項：

SELECT p1.*
FROM prod_id
INNER JOIN
(
    SELECT prod_id, MAX(price) AS price    -- this inner subquery finds the maximum
    FROM user_bid                          -- price for each product group
    GROUP BY prod_id
) p2
    ON p1.prod_id = p2.prod_id AND         -- and this join condition retains
       p1.price   = p2.price               -- only records which have this maximum
                                           -- price for each product group

這是一個使用子查詢的選項：

SELECT p1.*
FROM prod_id p1
WHERE price = (SELECT MAX(p2.price) FROM prod_id p2 WHERE p1.prod_id = p2.prod_id)

Answer 2

SELECT *
FROM user_bid 
WHERE (prodid, price) IN
(
    SELECT prodid, MAX(price)
    FROM user_bid 
    GROUP BY prod_id
)

Answer 3

對於SQL Server

;WITH cte AS

(
SELECT prod_id,price,user_id,
       ROW_NUMBER() OVER(PARTITION BY prod_id ORDER BY price desc) as rank
FROM table Name
)

SELECT prod_id,price,user_id
FROM cte
WHERE rank=1

Answer 4

使用以下查詢：

SELECT * FROM (SELECT * FROM user_bid  ORDER BY price DESC) AS Temp 
GROUP BY prod_id 

輸出：