Query with many CASE statements - optimization

Posted by Nemanja Vujacic on Stack Overflow See other posts from Stack Overflow or by Nemanja Vujacic
Published on 2010-12-24T13:37:59Z Indexed on 2010/12/24 16:54 UTC
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Hi guys,

I have one very dirty query that per sure can be optimized because there are so many CASE statements in it!

SELECT 
    (CASE pa.KplusTable_Id WHEN 1 THEN sp.sp_id 
          WHEN 2 THEN fw.fw_id
          WHEN 3 THEN s.sw_Id
          WHEN 4 THEN id.ia_id END) as Deal_Id,
max(CASE pa.KplusTable_Id WHEN 1 THEN sp.Trans_Id 
                          WHEN 2 THEN fw.Trans_Id
                          WHEN 3 THEN s.Trans_Id
                          WHEN 4 THEN id.Trans_Id END) as TransId_CurrentMax
INTO #MaxRazlicitOdNull
FROM #PotencijalniAktuelni pa LEFT JOIN kplus_sp sp (nolock) on sp.sp_id=pa.Deal_Id AND pa.KplusTable_Id=1
    LEFT JOIN kplus_fw fw (nolock) on fw.fw_id=pa.Deal_Id AND pa.KplusTable_Id=2        
    LEFT JOIN dev_sw s (nolock) on s.sw_Id=pa.Deal_Id AND pa.KplusTable_Id=3
    LEFT JOIN kplus_ia id (nolock) on id.ia_id=pa.Deal_Id AND pa.KplusTable_Id=4
WHERE isnull(CASE pa.KplusTable_Id WHEN 1 THEN sp.BROJ_TIKETA 
                                   WHEN 2 THEN fw.BROJ_TIKETA
                                   WHEN 3 THEN s.tiket
                                   WHEN 4 THEN id.BROJ_TIKETA END, '')<>'' 
GROUP BY CASE pa.KplusTable_Id WHEN 1 THEN sp.sp_id 
                               WHEN 2 THEN fw.fw_id
                               WHEN 3 THEN s.sw_Id
                               WHEN 4 THEN id.ia_id END

Because I have same condition couple times, do you have idea how to optimize query, make it simpler and better. All suggestions are welcome!

TnX in advance!

Nemanja

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