WHERE子句中的CASE表达式选择不为NULL的行

Question

I'm trying to write a query that when passed two variables, the first set is numbers 1-4 and the second set of number is 1-2. I want to select only the rows that meet the conditions. I've come up with this so far and am now a little lost on how to call the rows with my results.

DECLARE @Task INT 
DECLARE @Status INT 

SET @Task = 1 --Test Values can be 1,2,3,4
SET @Status = 1 -- Test Values can be 1,2

SELECT  
     Pics
    ,Title
    ,Photos
    ,Reports
FROM    
    DATES
WHERE   
    CASE 
       WHEN @Task = 1 AND @Status = 1 THEN Pics IS NOT NULL
       WHEN @Task = 2 AND @Status = 1 THEN Title IS NOT NULL 
       WHEN @Task = 3 AND @Status = 1 THEN Photos IS NOT NULL
       WHEN @Task = 4 AND @Status = 1 THEN Reports IS NOT NULL              
       ELSE NULL
    END

Sample data: Here is what i am using this for.

I have 2 drop down boxes, one called Tasks that hold the 4 values Pics, report, photos, title.

Second box holds the complete or not completed 1 or 2

I show all 4 Reports, titles, pics, photos when this query is called, but if i want to see all the reports that are done i can select the report value and then select the complete tab. example (Task)Report = 3 and (Status)complete = 1.

giving me all the reports that are done and still displaying the other 3 values even if they are null.

Answer 1

What you want is the eternally simple AND/OR:

DECLARE @Task INT 
DECLARE @Status INT 

SET @Task = 1 
SET @Status = 1

SELECT  
     Pics
    ,Title
    ,Photos
    ,Reports

FROM    DATES

WHERE @Status = 1
AND (
        (@Task = 1 AND Pics IS NOT NULL)
    OR
        (@Task = 2 AND Title IS NOT NULL)
    OR
        (@Task = 3 AND Photos IS NOT NULL)
    OR
        (@Task = 4 AND Reports IS NOT NULL) 
    )

Answer 2

Used @JohnHC example and worked off of that. I went with a CASE after all, because it did what i needed to do. here is the finished code. Thanks for all the info and help! If you think there is another way please let me know.

DECLARE @Task INT 
DECLARE @Status INT 

SET @Task = 1 --Test Values can be 1,2,3,4
SET @Status = 1 -- Test Values can be 1,2

SELECT  
      Pics
     ,Title
     ,Photos
     ,Reports
FROM    
      DATES

WHERE   1 = CASE WHEN @Task = 1 AND @Status = 1 AND Pics IS NOT NULL THEN 1 ELSE 0 END
      OR
        1 = CASE WHEN @Task = 1 AND @Status = 2 AND Pics IS NULL THEN 1 ELSE 0 END
      OR
        2 = CASE WHEN @Task = 2 AND @Status = 1 AND Reports IS NOT NULL THEN 2 ELSE 0 END
      OR
        2 = CASE WHEN @Task = 2 AND @Status = 2 AND Reports IS NULL THEN 2 ELSE 0 END
      OR
        3 = CASE WHEN @Task = 3 AND @Status = 1 AND Photos IS NOT NULL THEN 3 ELSE 0 END
      OR
        3 = CASE WHEN @Task = 3 AND @Status = 2 AND Photos IS NULL THEN 3 ELSE 0 END
      OR
        4 = CASE WHEN @Task = 4 AND @Status = 1 AND Title IS NOT NULL THEN 4 ELSE 0 END
      OR
        4 = CASE WHEN @Task = 4 AND @Status = 2 AND Title IS NULL THEN 4 ELSE 0 END
END