MySQL優化，多選到單選

Question

我有一個表，我需要在其中選擇一個周期總計的MAX（SUM（total））。

SELECT SUM(P.amount) as total FROM bank P WHERE P.ReceivedDate >= '2008-07-28' AND P.ReceivedDate <= '2008-08-31';

SELECT SUM(P.amount) as total FROM bank P WHERE P.ReceivedDate >= '2008-09-01' AND P.ReceivedDate <= '2008-09-28';

SELECT SUM(P.amount) as total FROM bank P WHERE P.ReceivedDate >= '2008-09-29' AND P.ReceivedDate <= '2008-10-26';

我已經運行了上述查詢，並在php中找到了最高的總數。

我不確定如何按此查詢分組。

我期望一個查詢將所有查詢替換為MAX（SUM（total））。

請幫幫我。

Answer 1

您可以嘗試類似

SELECT  TOP 1
        CASE
            WHEN P.ReceivedDate BETWEEN '2008-07-28' AND '2008-08-31' THEN 1
            WHEN P.ReceivedDate BETWEEN '2008-09-01' AND '2008-09-28' THEN 2
            WHEN P.ReceivedDate BETWEEN '2008-09-29' AND '2008-10-26' THEN 3
        END,
        SUM(P.amount) Total
FROM    bank p
GROUP BY CASE
            WHEN P.ReceivedDate BETWEEN '2008-07-28' AND '2008-08-31' THEN 1
            WHEN P.ReceivedDate BETWEEN '2008-09-01' AND '2008-09-28' THEN 2
            WHEN P.ReceivedDate BETWEEN '2008-09-29' AND '2008-10-26' THEN 3
        END

HAVING  CASE 
            WHEN P.ReceivedDate BETWEEN '2008-07-28' AND '2008-08-31' THEN 1 
            WHEN P.ReceivedDate BETWEEN '2008-09-01' AND '2008-09-28' THEN 2 
            WHEN P.ReceivedDate BETWEEN '2008-09-29' AND '2008-10-26' THEN 3 
        END IS NOT NULL
ORDER BY Total DESC

或更短的版本

SELECT  TOP 1
        SUM(amount) Total
FROM    (
            SELECT  CASE 
                        WHEN P.ReceivedDate BETWEEN '2008-07-28' AND '2008-08-31' THEN 1 
                        WHEN P.ReceivedDate BETWEEN '2008-09-01' AND '2008-09-28' THEN 2 
                        WHEN P.ReceivedDate BETWEEN '2008-09-29' AND '2008-10-26' THEN 3 
                    END GroupVal,
                    P.amount
            FROM    bank P
        ) Vals
GROUP BY Vals.GroupVal
HAVING  Vals.GroupVal IS NOT NULL
ORDER BY Total DESC