检查列 IS NULL 在案例表达式中不起作用

Question

I am trying to check a column which belongs to View "IS NULL" and it works good with select statement:

SELECT TOP (1000) [Invoice_Number]
  ,[Invoice_Date]
  ,[Invoice_Amount]
  ,[Invoice_CoCd]
  ,[Invoice_vendor]
  ,[Invoice_PBK]
  ,[Invoice_DType]
  ,[Invoice_DueDate]
  ,[Invoice_ClgDate] FROM [dbo].[viewABC] where   Invoice_PBK IS NULL

Now I have an update statement, where I need to update a column in a table based on NULL in VIEW:

UPDATE cis
    SET
    cis.InvoiceStatus = 
    (
    CASE 

    WHEN RTRIM(LTRIM(imd.[Invoice_PBK])) IS NULL THEN 
    'HELLO'  
    WHEN RTRIM(LTRIM(imd.Invoice_DType)) = 'RD' 
    THEN        '233'  END)
FROM 
    [dbo.[tblABC] cis,
    [dbo].[viewABC] imd 
WHERE [condition logic]

These is no issue with where condition, the IS NULL in the CASE expression causing the problem.

Can someone help please?

Answer 1

Voting to close this as typographical, but to show the OP their typo:

UPDATE cis
    SET cis.InvoiceStatus = CASE WHEN RTRIM(LTRIM(imd.[Invoice_PBK])) IS NULL THEN 'HELLO'  
                                 WHEN RTRIM(LTRIM(imd.Invoice_DType)) = 'RD' THEN  '233'
                            END
FROM 
    [dbo.[tblABC] cis,
    [dbo].[viewABC] imd --Stop using 30 year old syntax, it was replaced 30 years ago.
WHERE [condition logic]

And, as my comment says, stop using joins that are 27 years out of date. Bad habits to kick: using old-style JOINs

Answer 2

Looking at this expression:

cis.InvoiceStatus =
CASE 
    WHEN RTRIM(LTRIM(imd.[Invoice_PBK])) IS NULL THEN 
        'HELLO'  
    WHEN RTRIM(LTRIM(imd.Invoice_DType)) = 'RD' THEN
        '233'  
END

And this symptom:

CIS.InvoiceStatus gets updated with NULL

The obvious conclusion is neither WHEN condition is met, and therefore the result of the CASE expression is NULL .

Maybe you wanted this, which will preserve the original value in that situation:

cis.InvoiceStatus =
CASE 
    WHEN RTRIM(LTRIM(imd.[Invoice_PBK])) IS NULL THEN 
        'HELLO'  
    WHEN RTRIM(LTRIM(imd.Invoice_DType)) = 'RD' THEN
        '233'  
    ELSE
        cis.InvoiceStatus
END

Or maybe you wanted this, to also match an empty string value:

cis.InvoiceStatus =
CASE 
    WHEN NULLIF(RTRIM(LTRIM(imd.[Invoice_PBK])),'') IS NULL THEN 
        'HELLO'  
    WHEN RTRIM(LTRIM(imd.Invoice_DType)) = 'RD' THEN
        '233'  
END

It's also worth pointing out the two WHEN conditions are looking at two different columns.

Finally, it may be worth a data clean-up project here. Needing to do an LTRIM() will break any chance of using indexes on those fields ( RTRIM() is slightly less bad), and index use cuts to the core of database performance.

Answer 3

You may want to just test your Logic piece by piece. Try

SELECT ISNULL(RTRIM(LTRIM(imd.[Invoice_PBK])),'Hey Im Null')
FROM 
    [dbo].[tblABC] cis,
    [dbo].[viewABC] imd 
WHERE [condition logic]

See if you get that String value on your returned column(s) from the Query. Then, build from there. It could be something as simple as the JOIN . Which I'm not a fan of that old syntax but, without more info on this table other than [conditions] . It's hard to just guess an answer for you. You have no detailed evidence that helps us. It very well could be your conditions but, you're saying "condition logic" and that does nothing for the group on this thread.