Question

我在使用下面的存储过程查询检索准确的数据值时遇到问题：

    CREATE PROCEDURE usp_InvoiceErrorLog
    @RecID int
AS

DECLARE @ErrorString as varchar(1000),
        @ErrorCode as int;

Select @ErrorCode = ErrorCode from tbl_AcctRecv_WebRpt Where RecID = @RecID;
IF NOT(@ErrorCode = NULL)
    Begin
        Select @ErrorString = ErrorDesc from tbl_ErrDesc Where ErrorCode = @ErrorCode
    End

Select  RecID, VendorNum, VendorName, InvNum, InvTotal, (SELECT CONVERT(VARCHAR(11), InvDate, 106) AS [DD MON YYYY]) As InvDate,
        TicketRequestor, ErrorCode, @ErrorString as ErrorDesc
    from tbl_AcctRecv_WebRpt Where RecID =  @RecID

ErrorDesc列（在底部的最后一个select语句中）返回一个NULL值，它应该返回一个有效的字符串数据。

有什么想法吗？

Answer 1

IF NOT(@ErrorCode = NULL) - ALWAYS false(NULL)!

应该是

IF (@ErrorCode IS NOT NULL)

Answer 2

为什么不首先查询该行并仔细检查ErrorDesc是否实际包含值：

SELECT ErrorDesc WHERE RecID=@RecID

返回什么？如果为NULL则没有问题。

CREATE PROCEDURE usp_InvoiceErrorLog  
@RecID int  
AS

DECLARE @ErrorString as varchar(1000)
DECLARE @ErrorCode as int

Select @ErrorCode = (SELECT ErrorCode from tbl_AcctRecv_WebRpt Where RecID = @RecID) 

IF (@ErrorCode IS NOT NULL) 
Begin 
    --its NOT NULL
    Select @ErrorString = (SELECT ErrorDesc from tbl_ErrDesc Where ErrorCode = @ErrorCode)
End
--optional it IS NULL
ELSE
    BEGIN
       SELECT @ErrorString = (SELECT 'It Doesnt Contain Anything!')
    END

Select 
     RecID, 
     VendorNum, 
     VendorName, 
     InvNum, 
     InvTotal, 
     (SELECT CONVERT(VARCHAR(11), InvDate, 106) AS [DD MON YYYY]) As InvDate, 
     TicketRequestor, 
     ErrorCode, 
     @ErrorString as ErrorDesc 
FROM 
     tbl_AcctRecv_WebRpt 
Where 
     RecID = @RecID
END

这对我有用。看看你的if条件： IF NOT(@ErrorCode = NULL)并查看我的IF (@ErrorCode IS NOT NULL).你想使用IS NOT OR IS而不是当处理NULL时= =

SQL语法问题（多选）

2 个答案: