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COBOL -DB2 SQL code to have GROUP BY for CASE statement
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vinu78

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Posts: 170
Location: India

PostPosted: Wed Oct 23, 2019 7:00 pm    Post subject: COBOL -DB2 SQL code to have GROUP BY for CASE statement
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Hi All,

I wanted only unique rows to be extracted from below SQL statement that is in COBOL program.
Here the inner SQL query AB returns only unique row, however after it is LEFT JOIN with TABLE_B, it returns multiple rows.

Code:
SELECT
      A.CLAIM_NO,
     ,CASE
       WHEN LEFT(B.REMARKS,5) > B.CLAIM_NO THEN 'CC'
       WHEN RIGHT(B.CLAIM_NO,1) NOT BETWEEN 'A' AND 'T' THEN 'Z'
       ELSE 'A'
      END
      ,A.EFF_DATE
      ,A.STATUS
      ,:WS-CLAIM-DT-FROM
      ,:WS-CLAIM-DT-TO

FROM
     (SELECT ......) AS AB
       JOIN TABLE_A AS A
      ON A.CLAIM_NO = AB.CLAIM_NO

LEFT JOIN TABLE_B AS C
     ON C.ID_NO = AB.ID_NO
    AND C.FUNC_NO = AB.FUNC_NO

ORDER BY
     CASE WHEN WS-SORT-ORDER = 'E'  THEN A.EFF_DATE END
     CASE WHEN WS-SORT-ORDER = 'C' THEN A.CLAIM_NO  END



So adding GROUP BY should extract only unique rows. But I am getting error when GROUP BY was added for CASE statement and :WS-CLAIM-DT-FROM (this gets value from online screen).
Can you please help me how to have GROUP BY for CASE statement

Code:
SELECT
      A.CLAIM_NO,
     ,CASE
       WHEN LEFT(B.REMARKS,5) > B.CLAIM_NO THEN 'CC'
       WHEN RIGHT(B.CLAIM_NO,1) NOT BETWEEN 'A' AND 'T' THEN 'Z'
       ELSE 'A'
      END
      ,A.EFF_DATE
      ,A.STATUS
      ,:WS-CLAIM-DT-FROM
      ,:WS-CLAIM-DT-TO
FROM
     (SELECT ......) AS AB
       JOIN TABLE_A AS A
      ON A.CLAIM_NO = AB.CLAIM_NO
LEFT JOIN TABLE_B AS C
     ON C.ID_NO = AB.ID_NO
    AND C.FUNC_NO = AB.FUNC_NO
GROUP BY
     A.CLAIM_NO,
     ,CASE
       WHEN LEFT(B.REMARKS,5) > B.CLAIM_NO THEN 'CC'
       WHEN RIGHT(B.CLAIM_NO,1) NOT BETWEEN 'A' AND 'T' THEN 'Z'
       ELSE 'A'
      END
      ,A.EFF_DATE
      ,A.STATUS
      ,:WS-CLAIM-DT-FROM
      ,:WS-CLAIM-DT-TO
ORDER BY
     CASE WHEN WS-SORT-ORDER = 'E'  THEN A.EFF_DATE END
     CASE WHEN WS-SORT-ORDER = 'C' THEN A.CLAIM_NO  END


The above SQL works good while executed in SPUFI, but not inside COBOL program.

Thanks
Vinu
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Rohit Umarjikar

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Joined: 21 Sep 2010
Posts: 2296
Location: NY,USA

PostPosted: Thu Oct 24, 2019 12:02 am    Post subject:
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How about moving the entire CASE within "(SELECT ......) AS AB" and use this value in outer Select to which GROUP BY is applied?
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sergeyken

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Joined: 29 Apr 2008
Posts: 603
Location: Maryland

PostPosted: Thu Oct 24, 2019 1:55 am    Post subject: Re: COBOL -DB2 SQL code to have GROUP BY for CASE statement
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vinu78 wrote:
Here the inner SQL query AB returns only unique row, however after it is LEFT JOIN with TABLE_B, it returns multiple rows.

RTFM:

LEFT JOIN selects all records from the left table, and then appends only those records from right table where key(s) do match.

Total output size shall be mandatory the size of the left table (with optional WHERE selection).
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Rohit Umarjikar

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Posts: 2296
Location: NY,USA

PostPosted: Thu Oct 24, 2019 3:53 am    Post subject: Re: COBOL -DB2 SQL code to have GROUP BY for CASE statement
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sergeyken wrote:
vinu78 wrote:
Here the inner SQL query AB returns only unique row, however after it is LEFT JOIN with TABLE_B, it returns multiple rows.

RTFM:

LEFT JOIN selects all records from the left table, and then appends only those records from right table where key(s) do match.

Total output size shall be mandatory the size of the left table (with optional WHERE selection).

Not quite right.
If a left table ( Main Table) has 1 row matching with 5 rows of the right table ( Table used in left join) then 5 rows are returned as a part of the Join. So always a Null handling is recommended for any cols coming out of this right table and distinct or group by is used to remove duplicates.

OPs problem is Group By rule violation because of the CASE statement used in the select. Another solution apart from what I suggested is to try MIN/MAX around CASE and should work.
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vinu78

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PostPosted: Thu Oct 24, 2019 1:00 pm    Post subject:
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Hi Rohit,

I have tried moving the entire CASE within "(SELECT ......) AS AB" however I was getting abend as "AS" is invalid. Then I had the entire CASE statement as such in SELECT and also in GROUP BY without AS "AB". This time i am getting Bind error. (SQLCODE=-312 SQLSTATE=42618 )

Is there any other way to achieve this

Thanks
Vinu
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Rohit Umarjikar

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Joined: 21 Sep 2010
Posts: 2296
Location: NY,USA

PostPosted: Thu Oct 24, 2019 8:05 pm    Post subject:
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Quote:
I have tried moving the entire CASE within "(SELECT ......) AS AB" however I was getting abend as "AS" is invalid.
This is very poor information that you provided.
Post the complete SQL that you have tried and specially"(SELECT ......) AS AB", You probably be doing some syntax errors and only way to know that is when we can see it what you tried than believe what you say.

Quote:
The above SQL works good while executed in SPUFI, but not inside COBOL program.

Out of curiosity, Where is the B table and shouldn't CASE refers to AB instead?
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sergeyken

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Location: Maryland

PostPosted: Thu Oct 24, 2019 9:50 pm    Post subject: Re: COBOL -DB2 SQL code to have GROUP BY for CASE statement
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vinu78 wrote:
The above SQL works good while executed in SPUFI, but not inside COBOL program.

This is an obvious bullshit.

The given SQL is real garbage; no intention to dig into it.

If such sort of SQL is needed to produce some useful result, then definitely the approach itself must be changed, and/or data structure(s) re-organized, to fit the business requirements.
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Rohit Umarjikar

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Posts: 2296
Location: NY,USA

PostPosted: Fri Oct 25, 2019 2:25 am    Post subject:
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While you answer my question and post the comple sql, try this and let us know
Quote:

"Another solution apart from what I suggested is to try MIN/MAX around CASE and should work."
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vinu78

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Posts: 170
Location: India

PostPosted: Tue Oct 29, 2019 4:32 pm    Post subject: Reply to: COBOL -DB2 SQL code to have GROUP BY for CASE statement
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Hi Rohit,

Can you please help me with the MIN/MAX for CASE statement syntax. I have tried and was not able to get it right

Thanks
Vinu
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Rohit Umarjikar

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Joined: 21 Sep 2010
Posts: 2296
Location: NY,USA

PostPosted: Tue Oct 29, 2019 7:56 pm    Post subject:
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Quote:
Can you please help me with the MIN/MAX for CASE statement syntax. I have tried and was not able to get it right

What is the SQLCODE? I can't help you if you don't post the complete SQL you tried and keep overlooking what is being asked repeatedly.
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vinu78

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Joined: 02 Oct 2008
Posts: 170
Location: India

PostPosted: Wed Oct 30, 2019 5:55 pm    Post subject:
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Hi Rohit,

I have commented out CASE statements in SELECT and GROUP BY and also commented out ORDER BY statement and also commented Host variable :WS-CLAIM-DT-FROM and :WS-CLAIM-DT-TO and it ran fine.
As first step, I just kept the host variables in both SELECT and GROUP By to see whether SQL is running and unfortunately it gave Bidn error with SQL CODE -312 with SQLSTATE 42618

Code:
  SELECT
        A.CLAIM_NO,
*       ,CASE
*         WHEN LEFT(B.REMARKS,5) > B.CLAIM_NO THEN 'CC'
*       WHEN RIGHT(B.CLAIM_NO,1) NOT BETWEEN 'A' AND 'T' THEN 'Z'
*         ELSE 'A'
*        END
      ,A.EFF_DATE
      ,A.STATUS
      ,:WS-CLAIM-DT-FROM
      ,:WS-CLAIM-DT-TO
  FROM
       (SELECT ......) AS AB
         JOIN TABLE_A AS A
        ON A.CLAIM_NO = AB.CLAIM_NO
  LEFT JOIN TABLE_B AS C
       ON C.ID_NO = AB.ID_NO
      AND C.FUNC_NO = AB.FUNC_NO
  GROUP BY
       A.CLAIM_NO,
*       ,CASE
*        WHEN LEFT(B.REMARKS,5) > B.CLAIM_NO THEN 'CC'
*         WHEN RIGHT(B.CLAIM_NO,1) NOT BETWEEN 'A' AND 'T' THEN 'Z'
*         ELSE 'A'
*        END
        ,A.EFF_DATE
        ,A.STATUS
        ,:WS-CLAIM-DT-FROM
        ,:WS-CLAIM-DT-TO
*   ORDER BY
*       CASE WHEN WS-SORT-ORDER = 'E'  THEN A.EFF_DATE END
*       CASE WHEN WS-SORT-ORDER = 'C' THEN A.CLAIM_NO  END


Please advice. I will uncomment CASE statement after this gets fixed.

Thanks
Vinu
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Marso

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Joined: 13 Mar 2006
Posts: 1330
Location: Israel

PostPosted: Wed Oct 30, 2019 6:10 pm    Post subject: Re: COBOL -DB2 SQL code to have GROUP BY for CASE statement
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vinu78 wrote:
Code:
SELECT
      A.CLAIM_NO,
     ,CASE


Code:
SELECT
      A.CLAIM_NO,
     ,CASE

GROUP BY
     A.CLAIM_NO,
     ,CASE


Is that a typo ???
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vinu78

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Posts: 170
Location: India

PostPosted: Wed Oct 30, 2019 6:33 pm    Post subject:
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Sorry. Yes thatz a typo.
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Rohit Umarjikar

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Joined: 21 Sep 2010
Posts: 2296
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PostPosted: Fri Nov 01, 2019 2:42 am    Post subject:
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You still refusing to post complete SQL and specially what is the full query here (SELECT ......) as AB.
Second when you move CASE within this SELECT above ( and once you share that complete sql) tell us the sqlcode. Don't try anything else but only this change.

If you can not do that simple thing then this post will eventually get locked soon as it is going nowhere.
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vinu78

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Posts: 170
Location: India

PostPosted: Fri Nov 01, 2019 5:03 pm    Post subject:
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Rohit,

Sorry. Please see the complete SQL with CASE statement also included

Code:
  SELECT
        A.CLAIM_NO
        ,CASE
          WHEN LEFT(B.REMARKS,5) > B.CLAIM_NO THEN 'CC'
        WHEN RIGHT(B.CLAIM_NO,1) NOT BETWEEN 'A' AND 'T' THEN 'Z'
          ELSE 'A'
         END
      ,A.EFF_DATE
      ,A.STATUS
      ,:WS-CLAIM-DT-FROM
      ,:WS-CLAIM-DT-TO
  FROM
       (SELECT B.CLAIM_NO,
               B.ID_NO,
               B.FUNC_NO
          FROM TABLE_A AS B
         WHERE B.CD_ANALYST = '01'
           AND B.DEPT_NO = :WS-DEPT-NO
         GROUP BY B.CLAIM_NO) AS AB
   JOIN TABLE_A AS A
      ON A.CLAIM_NO = AB.CLAIM_NO
   LEFT JOIN TABLE_B AS C
     ON C.ID_NO = AB.ID_NO
    AND C.FUNC_NO = AB.FUNC_NO
  GROUP BY
       A.CLAIM_NO,
        ,CASE
         WHEN LEFT(B.REMARKS,5) > B.CLAIM_NO THEN 'CC'
          WHEN RIGHT(B.CLAIM_NO,1) NOT BETWEEN 'A' AND 'T' THEN 'Z'
          ELSE 'A'
         END
        ,A.EFF_DATE
        ,A.STATUS
        ,:WS-CLAIM-DT-FROM
        ,:WS-CLAIM-DT-TO
*   ORDER BY
*       CASE WHEN WS-SORT-ORDER = 'E'  THEN A.EFF_DATE END
*       CASE WHEN WS-SORT-ORDER = 'C' THEN A.CLAIM_NO  END


After executing it, I got the SQL code as
SQLCODE=-312
SQLSTATE=42618

Thanks
Vinu
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sergeyken

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Posts: 603
Location: Maryland

PostPosted: Fri Nov 01, 2019 11:20 pm    Post subject:
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Any code which is complex enough (based on the experience of its author) must be debugged step-by-step:

1) Prepare test data with limited number of rows, and eliminate all parts (fields, or whatever) which are not critical for this particular test.

2) Split any complex SQL (or any other code!) into component parts, to be able to run them separately; start from the most "inner" parts of your code.

3) Try to run each elementary part with your test data, and carefully verify all intermediate results, in minor details!

4) If you are satisfied with the results of a "unit test" of #3 above, then add the next smallest possible part of the "complete query" to your "unit test", and carefully repeat #3 with new enhanced code.

5) Don't forget, and don't be lazy verifying all intermediate results, in minor details!

6) When all original code is included into your "unit test", then re-run it with production-size testing data.

7) If you don't like, or don't want, or just cannot follow the steps suggested above, then I would recommend you to change your job, instead of asking the forum to perform your job duties for you.

Good luck.
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Rohit Umarjikar

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PostPosted: Sat Nov 02, 2019 12:00 am    Post subject:
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Your query is in very bad shape and I don't know what are you trying to achieve with this sql. You don't need Left outer Join because none of the columns are being referred in the SELECT from it. Second you are trying to access B. something when you should use AB. something . Basically you had many basic errors in your sql.

I tried to simplify per my understanding and wrote this, try it to see if it works.
Code:

SELECT
       Main_Table.CLAIM_NO,
       Main_Table.ID_NO,
       Main_Table.FUNC_NO,
       CASE
         WHEN LEFT(Main_Table..REMARKS,5) > Main_Table..CLAIM_NO THEN 'CC'
         WHEN RIGHT(Main_Table..CLAIM_NO,1) NOT BETWEEN 'A' AND 'T' THEN 'Z '
          ELSE 'A '
       END,
       Main_Table.EFF_DATE,
       Main_Table.STATUS 
FROM
        (SELECT DISTINCT B.CLAIM_NO,
               B.ID_NO,
               B.FUNC_NO,
               B.REMARKS,
               A.EFF_DATE,
               A.STATUS,
              :WS-CLAIM-DT-FROM as DT_FRM,
              :WS-CLAIM-DT-TO as FT_TO
          FROM TABLE_A AS B 
         WHERE B.CD_ANALYST = '01'
           AND B.DEPT_NO = :WS-DEPT-NO
           AND EXISTS (SELECT 1 from TABLE_A AS A Where A.CLAIM_NO = B.CLAIM_NO)) Main_Table
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vinu78

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PostPosted: Sun Nov 03, 2019 10:25 am    Post subject:
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Thanks Sergekeyn for the suggestion. Will follow that.

Rohit,

Thanks for the revised SQL. I certainly understood that the SQL is in bad shape and it is an existing written SQL years back. The SQL used to be running fine. The inner SELECT returns only 1 row. Since the LEFT JOIN returns multiple row, the total SQL output returns duplicate rows and is an issue. So to remove duplicate rows, I thought just GROUP BY will solve this issue. But GROUP BY is not working correctly for CAST statement and HOST variables.
So as short term fix, if we were able to get this GROUP BY for CASE and Host variable fixed, it will be of great help. Eventually as per your suggestion, I will go ahead and rewrite this existing SQL.

Thanks
Vinu
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Rohit Umarjikar

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PostPosted: Sun Nov 03, 2019 10:41 am    Post subject: Reply to: COBOL -DB2 SQL code to have GROUP BY for CASE statement
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But you must understand that LEFT OUTER JOIN is not needed anymore since there are no columns referenced in the SELECT from it. It does not matter if it’s working and existing as over a period of time that JOIN became obsolete.
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vinu78

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PostPosted: Sun Nov 03, 2019 5:32 pm    Post subject:
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Rohit,

Sorry. LEFT JOIN is mandatory since we have one more condition in it SUPP_TYPE IN ('U', 'V')as mentioned in below SQL. I purposefully didn't mention earlier to reduce the SQL complexity. Since you have mentioned above regarding LEFT JOIN neccessity, I just mentioned the condition in below SQL.

Code:
SELECT
        A.CLAIM_NO
        ,CASE
          WHEN LEFT(B.REMARKS,5) > B.CLAIM_NO THEN 'CC'
        WHEN RIGHT(B.CLAIM_NO,1) NOT BETWEEN 'A' AND 'T' THEN 'Z'
          ELSE 'A'
         END
      ,A.EFF_DATE
      ,A.STATUS
      ,:WS-CLAIM-DT-FROM
      ,:WS-CLAIM-DT-TO
  FROM
       (SELECT B.CLAIM_NO,
               B.ID_NO,
               B.FUNC_NO
          FROM TABLE_A AS B
         WHERE B.CD_ANALYST = '01'
           AND B.DEPT_NO = :WS-DEPT-NO
         GROUP BY B.CLAIM_NO) AS AB
   JOIN TABLE_A AS A
      ON A.CLAIM_NO = AB.CLAIM_NO
   LEFT JOIN TABLE_B AS C
     ON C.ID_NO = AB.ID_NO
    AND C.FUNC_NO = AB.FUNC_NO
    AND  C.SUPP_TYPE IN ('U','V')
  GROUP BY
       A.CLAIM_NO,
        ,CASE
         WHEN LEFT(B.REMARKS,5) > B.CLAIM_NO THEN 'CC'
          WHEN RIGHT(B.CLAIM_NO,1) NOT BETWEEN 'A' AND 'T' THEN 'Z'
          ELSE 'A'
         END
        ,A.EFF_DATE
        ,A.STATUS
        ,:WS-CLAIM-DT-FROM
        ,:WS-CLAIM-DT-TO
*   ORDER BY
*       CASE WHEN WS-SORT-ORDER = 'E'  THEN A.EFF_DATE END
*       CASE WHEN WS-SORT-ORDER = 'C' THEN A.CLAIM_NO  END

So it will be appreciated, if you can let me know how we can have GROUP BY for the CASE statement and Host variables declared in SELECT statement.


Thanks
Vinu
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