在SELECT中使用CASE的SQL查詢不起作用

Question

我有一個更大的復雜查詢的這一部分：

SELECT SUM(pir.priceChange) AS CASE 
WHEN (SUM(pir.priceChange) > 0) THEN sellSum 
WHEN (SUM(pir.priceChange) < 0) THEN priceSum 
END

每當我嘗試通過PDO將其傳遞給MySQL（MyISAM）時，它會拋出異常：

語法錯誤或訪問沖突：1064 SQL語法中有錯誤; 查看與您的MySQL服務器版本對應的手冊，以便在'（SELECT SUM（pir.priceChange）AS CASE WHEN（SUM（pir.priceChange）> 0）附近使用正確的語法。然后在第17行使用sellSu'

我想這與我試圖錯誤地使用CASE語句這一事實有關。 真的很想知道出了什么問題，提前謝謝。

編輯：我的完整查詢（無任何情況編輯）：

SELECT  pi.id AS id,
pi.type AS type,
pi.parValue AS rating,
pi.duration AS time,
countAmt.amt AS amtSold,
IFNULL(pii.pChange,
0) AS priceTotal,
0) AS costTotal,
IFNULL(pii.selfPrice,
0) AS costPrice,
(IFNULL(pii.sellSum,
0) - IFNULL(pii.selfPrice,
0)) AS profit,
countClose.amtClosed AS amtClosed
FROM salon.paymentInstrument as pi
(SELECT SUM(pir.priceChange) AS pChange,
SUM(pir.costChange) AS cChange,
(IFNULL(pir.priceChange,
0) - IFNULL(pir.costChange,
0)) AS selfPrice,
pii.paymentInstrumentID
FROM salon.paymentInstrumentRegister as pir
JOIN salon.paymentInstrumentItem as pii ON pir.paymentInstrumentItemID = pii.id
WHERE pir.date >= '2014-04-11'
AND pir.date <= '2014-04-25'
GROUP BY pii.paymentInstrumentID 
) as pii
(SELECT pii.paymentInstrumentID,
COUNT(*) AS amtClosed
FROM salon.paymentInstrumentItem as pii
WHERE pii.annulTime >= 2014-04-11
AND pii.annulTime <= 2014-04-25
AND pii.status <> "active"
GROUP BY pii.paymentInstrumentID 
) as countClose
(SELECT pii.paymentInstrumentID,
COUNT(*) AS amt
FROM salon.paymentInstrumentItem as pii
WHERE pii.startTime >= 2014-04-11
AND pii.startTime <= 2014-04-25
GROUP BY pii.paymentInstrumentID 
) as countAmt

抱歉格式不正確，它是用PHP動態生成的。 我有一種感覺，我在查詢中的其他地方犯了一個錯誤。

Answer 1

試試這種方式：

SELECT CASE WHEN SUM(pir.priceChange)>0 THEN SUM(pir.priceChange) END as SumPrice,
       CASE WHEN SUM(pir.priceChange)<0 THEN SUM(pir.priceChange) END as priceSum
FROM TableName

SQL Fiddle中的一個例子。

Answer 2

嘗試這個：

SELECT CASE 
WHEN (SUM(pir.priceChange) > 0) THEN sellSum 
WHEN (SUM(pir.priceChange) < 0) THEN priceSum 
END