同じテーブルのProductIDに基づいて、新しい列で「現金」、「小切手」、および「クレジットカード」の合計を取得しようとしています。
表-支払い
+-----------+------------+---------------+--------+
| ProductID | SaleDate | PaymentMethod | Amount |
+-----------+------------+---------------+--------+
| 3 | 2012-02-10 | Cash | 10 |
| 3 | 2012-02-10 | Cash | 10 |
| 3 | 2012-02-10 | Check | 15 |
| 3 | 2012-02-10 | Credit Card | 25 |
| 4 | 2012-02-10 | Cash | 5 |
| 4 | 2012-02-10 | Check | 6 |
| 4 | 2012-02-10 | Credit Card | 7 |
+-----------+------------+---------------+--------+
望ましい出力-
+------------+------+-------+-------------+-------+
| ProductID | Cash | Check | Credit Card | Total |
+------------+------+-------+-------------+-------+
| 3 | 20 | 15 | 25 | 60 |
| 4 | 5 | 6 | 7 | 18 |
+------------+------+-------+-------------+-------+
同じテーブルをLEFT JOINしてみましたが、成功していません。任意の提案をいただければ幸いです。ありがとう。
失敗した不完全な試行-
SELECT P.ProductID, Sum( PCash.Amount ) AS 'Cash', SUM( PCheck.Amount ) AS 'Check', SUM( PCredit.Amount) AS 'Credit Card'
FROM Payments AS P
LEFT JOIN Payments AS PCash ON P.ProductID = PCash.ProductID AND PCash.PaymentMethod = 'Cash'
LEFT JOIN Payments AS PCheck ON P.ProductID = PCheck.ProductID AND PCheck.PaymentMethod = 'Check'
LEFT JOIN Payments AS PCredit ON P.ProductID = PCredit.ProductID AND PCredit.PaymentMethod = 'Credit'
WHERE P.SaleDate = '2012-02-10' GROUP BY ProductID;
これを必要以上に複雑にしていると思います。
SELECT
ProductID,
SUM(IF(PaymentMethod = 'Cash', Amount, 0)) AS 'Cash',
-- snip
SUM(Amount) AS Total
FROM
Payments
WHERE
SaleDate = '2012-02-10'
GROUP BY
ProductID
これは少し複雑に見えるかもしれませんが、まさにあなたが望むことをします
SELECT
DISTINCT(p.`ProductID`) AS ProductID,
SUM(pl.CashAmount) AS Cash,
SUM(pr.CashAmount) AS `Check`,
SUM(px.CashAmount) AS `Credit Card`,
SUM(pl.CashAmount) + SUM(pr.CashAmount) +SUM(px.CashAmount) AS Amount
FROM
`payments` AS p
LEFT JOIN (SELECT ProductID,PaymentMethod , IFNULL(Amount,0) AS CashAmount FROM payments WHERE PaymentMethod = 'Cash' GROUP BY ProductID , PaymentMethod ) AS pl
ON pl.`PaymentMethod` = p.`PaymentMethod` AND pl.ProductID = p.`ProductID`
LEFT JOIN (SELECT ProductID,PaymentMethod , IFNULL(Amount,0) AS CashAmount FROM payments WHERE PaymentMethod = 'Check' GROUP BY ProductID , PaymentMethod) AS pr
ON pr.`PaymentMethod` = p.`PaymentMethod` AND pr.ProductID = p.`ProductID`
LEFT JOIN (SELECT ProductID, PaymentMethod , IFNULL(Amount,0) AS CashAmount FROM payments WHERE PaymentMethod = 'Credit Card' GROUP BY ProductID , PaymentMethod) AS px
ON px.`PaymentMethod` = p.`PaymentMethod` AND px.ProductID = p.`ProductID`
GROUP BY p.`ProductID` ;
出力
ProductID | Cash | Check | Credit Card | Amount
-----------------------------------------------
3 | 20 | 15 | 25 | 60
4 | 5 | 6 | 7 | 18
例を使用したSUM CASE:
SELECT
DISTINCT(p.`ProductID`) AS ProductID,
SUM(IF(p.`PaymentMethod`='Cash',Amount,0)) AS Cash_,
SUM(IF(p.`PaymentMethod`='Check',Amount,0)) AS Check_,
SUM(IF(p.`PaymentMethod`='Credit Card',Amount,0)) AS Credit_Card_,
SUM( CASE PaymentMethod
WHEN 'Cash' THEN Amount
WHEN 'Check' THEN Amount
WHEN 'Credit Card' THEN Amount
END) AS Total
FROM
`payments` AS p
GROUP BY p.`ProductID`;
SQL FIDDLE: http://www.sqlfiddle.com/#!9/23d07d/18