SUM上的NULL值存在SQL問題

Question

我目前正在研究一些sql的東西，但在某個問題上運行。

我有這種方法，尋找現金交易，並摘下現金返還，但有時沒有現金交易，使價值變成了空值，你不能從NULL減去。 我試過在它周圍放置一個ISNULL，但它仍然變爲空。

任何人都可以幫助我嗎？

;WITH tran_payment AS 
(
SELECT 1 AS payment_method, NULL AS payment_amount, null as tran_header_cid 
UNION ALL 
SELECT 998 AS payment_method, 2 AS payment_amount, NULL as tran_header_cid 
), 
paytype AS 
(
SELECT 1 AS mopid, 2 AS mopshort 
), 
tran_header AS 
(
SELECT 1 AS cid 
) 
      SELECT p.mopid      AS mopid, 
        p.mopshort     AS descript, 
        payment_value AS PaymentValue, 
        ISNULL(DeclaredValue, 0.00) AS DeclaredValue 
      from paytype p 
        LEFT OUTER JOIN (SELECT CASE 
         When (tp.payment_method = 1) 
         THEN 
        (ISNULL(SUM(tp.payment_amount), 0) 
        - (SELECT ISNULL(SUM(ABS(tp.payment_amount)), 0) 
          FROM tran_payment tp 
          INNER JOIN tran_header th on tp.tran_header_cid = th.cid 
     WHERE payment_method = 998 
     )) 
    ELSE SUM(tp.payment_amount) 
    END as payment_value, 
    tp.payment_method, 
    0 as DeclaredValue 
    FROM tran_header th 
    LEFT OUTER JOIN tran_payment tp 
    ON tp.tran_header_cid = th.cid 
    GROUP BY payment_method) pmts 
    ON p.mopid = pmts.payment_method 

Answer 1

也許COALESCE()可以幫助你嗎？

你可以試試這個：

SUM(COALESCE(tp.payment_amount, 0)) 

或

COALESCE(SUM(tp.payment_amount), 0) 

COALESCE(arg1, arg2, ..., argN)返回列表中的第一個非空參數。

Answer 2

試圖把裏面ISNULL SUM和ABS也就是圍繞實際的現場，像這樣

SUM(ISNULL(tp.payment_amount, 0)) 

SUM(ABS(ISNULL(tp.payment_amount, 0))) 

Answer 3

我沒有MS SQL在這裏做測試，但將努力把ISNULL圍繞着SELECT？也許，ISNULL根本沒有被觸發，如果沒有匹配的行...