Sql Server Where Case Then Is Null Else Is Not Null

I have a procedure which receive a bit variable called @FL_FINALIZADA.

If it is null or false I want to restrict my select to show only the row开发者_如何学Gos that contain null DT_FINALIZACAO values. Otherwise I want to show the rows containing not null DT_FINALIZACAO values.

Something like this:

SELECT 
    * 
FROM 
    MyTable 
WHERE 
    ...
    AND
    (
        OPE.DT_FINALIZACAO = (
            CASE
                WHEN (@FL_FINALIZADA <> 1)
                    THEN NULL
                END
        ) OR 
        OPE.DT_FINALIZACAO IS NOT NULL
    )

In this case I receive the message:

None of the result expressions in a CASE specification can be NULL.

How can I achieve this?

Thanks in advance.

SELECT 
    * 
FROM 
    MyTable 
WHERE
    (ISNULL(@FL_FINALIZADA, 0) = 0
     AND
     OPE.DT_FINALIZACAO IS NULL
     )
     OR
     (@FL_FINALIZADA = 1
      AND
      OPE.DT_FINALIZACAO IS NOT NULL
     )

Change the AND to be:

AND (((@FL_FINALIZADA <> 1) AND (OPE.DT_FINALIZACAO IS NULL)) OR ( (@FL_FINALIZADA = 1) AND (OPE.DT_FINALIZACAO IS NOT NULL)))

If the bit flag is 1 then DT_FINALIZACAO can't be null.

IF @FL_FINALIZADA IS NULL
    SET @FL_FINALIZADA = 0

SELECT * FROM NewsletterSubscribers 
WHERE
   (@FL_FINALIZADA = 0 AND OPE.DT_FINALIZACAO IS NULL) 
   OR 
   (@FL_FINALIZADA = 1 AND OPE.DT_FINALIZACAO IS NOT NULL)

My detailed SQL is a little rusty, but have you tried using 0 insted of NULL? I would expect 0 to evaluate the same as NULL in that select