SQL Server函數總是返回NULL

Question

我在這裏拉我的頭髮。下面的函數總是返回null，即使它能正常工作，如果我將代碼拖出到查詢窗口並手動設置輸入參數。這個想法是，我有一個基於月份的不同查詢，因爲每個月的平均值都存儲在不同的列中。我知道，桌子的標準化程度不是很好，但這是我必須努力的。我錯過了什麼？

ALTER FUNCTION [dbo].[fn_currentShareBal] 
(
@currentDate datetime, 
@account  integer, 
@acctType  varchar 
) 
RETURNS money AS 
BEGIN 

DECLARE @dte char(10) 
DECLARE @returnVal money 
DECLARE @month int 

SET @dte = CONVERT(char(10), @currentDate, 101) 
SET @month = MONTH(@currentDate) 

-- because of the table strucure the actual query depends on the month 
IF @month = 1 SET @returnVal = (SELECT SUM(avg1) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 2 SET @returnVal = (SELECT SUM(avg2) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 3 SET @returnVal = (SELECT SUM(avg3) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 4 SET @returnVal = (SELECT SUM(avg4) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 5 SET @returnVal = (SELECT SUM(avg5) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 6 SET @returnVal = (SELECT SUM(avg6) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 7 SET @returnVal = (SELECT SUM(avg7) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 8 SET @returnVal = (SELECT SUM(avg8) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 9 SET @returnVal = (SELECT SUM(avg9) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 10 SET @returnVal = (SELECT SUM(avg10) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 11 SET @returnVal = (SELECT SUM(avg11) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

IF @month = 12 SET @returnVal = (SELECT SUM(avg12) 
         FROM COSHAVG 
         WHERE cuID = @account 
         AND avgBalanceMonth = @dte 
         AND acctType = @acctType) 

RETURN @returnVal 

END 
GO 

Answer 1

我認爲問題出在你的函數定義上。很難說因爲你沒有發佈你的表的定義。

這是行不通的？如果沒有，您可以在COSHAVG表上發佈腳本創建嗎？

ALTER FUNCTION [dbo].[fn_currentShareBal] 
(
    @currentDate datetime, 
    @account  integer, 
    @acctType  varchar(50) 
) 
RETURNS money 
AS 
BEGIN 
    DECLARE @dte varchar(20) 
    DECLARE @returnVal money 
    DECLARE @month int 

    SET @dte = CONVERT(varchar, @currentDate, 101) 
    SET @month = MONTH(@currentDate) 

    SELECT 
     @returnVal=SUM(CASE 
      WHEN @month = 1 THEN avg1 
      WHEN @month = 2 THEN avg2 
      WHEN @month = 3 THEN avg3 
      WHEN @month = 4 THEN avg4 
      WHEN @month = 5 THEN avg5 
      WHEN @month = 6 THEN avg6 
      WHEN @month = 7 THEN avg7 
      WHEN @month = 8 THEN avg8 
      WHEN @month = 9 THEN avg9 
      WHEN @month = 10 THEN avg10 
      WHEN @month = 11 THEN avg11 
      WHEN @month = 12 THEN avg12 
     END) 
    FROM COSHAVG 
    WHERE cuID = @account 
    AND avgBalanceMonth = @dte 
    AND acctType = @acctType 

    RETURN @returnVal 
END 
GO 

Answer 2

其他人所指出的事情，尋找在評論，但這裏的重寫功能（在行爲沒有真正改變，只是更容易保持）一個更清潔的方式：

ALTER FUNCTION [dbo].[fn_currentShareBal] 
    (
     @currentDate DATETIME 
    , @account INTEGER 
    , @acctType VARCHAR (100) 
    ) 
RETURNS MONEY 
AS 
    BEGIN 
     DECLARE @dte CHAR(10) 
     DECLARE @returnVal MONEY 
     DECLARE @month INT 
     SET @dte = CONVERT(CHAR(10), @currentDate, 101) 
     SET @month = MONTH(@currentDate) 
     -- because of the table strucure the actual query depends on the month 

     SELECT @returnVal = SUM(CASE WHEN @month = 1 THEN avg1 
             WHEN @month = 2 THEN avg2 
            /*...*/ 
             WHEN @month = 12 THEN avg12 
           END) 
     FROM COSHAVG 
     WHERE cuID = @account 
       AND avgBalanceMonth = @dte 
       AND acctType = @acctType 


     RETURN @returnVal 
    END