SQL：與MN

Question

巢SUM我有這樣一個簡單的SQL語句下面，我想窩聚合函數SUM和MIN：

SELECT SUM(MIN(r1.price)) 
FROM rounds r1, rounds r2 
WHERE r1.round ='1' 
AND r1.market = r2.market 
AND r1.round = r2.round 
AND r1.name = r2.name 
GROUP BY market 

不幸的是，這是行不通的。

Answer 1

嘗試：

SELECT SUM(lowest_price) FROM 
(SELECT MIN(r1.price) AS lowest_price 
FROM rounds r1 
INNER JOIN rounds r2 ON r1.market = r2.market 
        AND r1.round = r2.round 
        AND r1.name = r2.name 
WHERE r1.round ='1' 
GROUP BY r1.market) innerSElect 

Answer 2

如果您選擇的服務器產品的SQL風味支持排序功能，你也可以使用這樣的查詢：

SELECT SUM(price) 
FROM (
    SELECT 
    r1.price, 
    ROW_NUMBER() OVER (PARTITION BY r1.market ORDER BY r1.price) AS rnk 
    FROM rounds r1 
    INNER JOIN rounds r2 ON r1.market = r2.market 
         AND r1.round = r2.round 
         AND r1.name = r2.name 
    WHERE r1.round = '1' 
) s 
WHERE rnk = 1