當在SQL Server 2008中填充表時在兩列上使用SUM函數時返回NULL值

Question

INSERT INTO table正在爲返回的記錄集生成NULL值。我試圖從用戶庫表中添加SUM(m.earnings + m.fpearn) from pfinancial表和userid & minpay。

我在做什麼錯？還有更好的方式來重申通過id的臨時表嗎？

從表下面我應該填充publsher_monthly表，每個用戶ID一個唯一的ID，從userbase的minpay量和m.earnings + m.fpearn列從pfinancial表

publisher_monthly表

pmuseris pmminpay pmearnings 
5   20   75 
6   30   27 

總和

userbase表

userid minpay 
5  20 
6  30 

pfinancial表

userid earnings fpearn 
5  10   30 
5  20   15 
6  15   12 

我的查詢：

DECLARE @realuserid bigint 

CREATE TABLE #tmppmuserids(
    idx bigint Primary Key IDENTITY(1,1), 
    tmppmuserid bigint NULL 
) 

INSERT INTO #tmppmuserids 
    SELECT DISTINCT userid FROM pfinancial 

DECLARE @i bigint 
DECLARE @numrows bigint 

SET @i = 1 
SET @numrows = (SELECT COUNT(*) FROM #tmppmuserids) 

IF @numrows > 0 

WHILE (@i <= (SELECT MAX(idx) FROM #tmppmuserids)) 
BEGIN 
    SET @realuserid = (SELECT tmppmuserid FROM #tmppmuserids WHERE idx = @i) 

    --PROBLEM HERE 
    INSERT INTO publisher_monthly (pmearnings, pmuserid, pmminpay) 

    SELECT 
     SUM(m.earnings + m.fpearn), MAX(@realuserid), MAX(u.minpay) 
    FROM pfinancial m 
    INNER JOIN userbase u on u.userid = m.userid 
    WHERE 
     m.userid = @realuserid AND 
     (m.created >= DATEADD(MONTH, DATEDIFF(MONTH, -1, GETDATE()),0)) AND 
     (m.created < DATEADD(MONTH, DATEDIFF(MONTH, -1, GETDATE()) + 1, 0)) 
    --END PROBLEM 

    SET @i = @i + 1 
END 

SELECT * FROM #tmppmuserids 
SELECT * FROM publisher_monthly 

DROP TABLE #tmppmuserids 

Answer 1

廣場周圍的IsNull：

SELECT SUM(IsNull(m.earnings, 0) + IsNull(m.fpearn, 0)) 

，甚至周圍的整個事情：

SELECT IsNull(SUM(m.earnings + m.fpearn), 0)