Question

select statement in a cursor brings a different result or hangs

Asked by: shepp_it

I have following SQL code. It works fine but when I put this code into a cursor, "select cursor(<select statment>)mycur from dual", screen hangs.

I have also seen in some cases where the select statement shows different output than "select cursor(<select statement>)mycur from dual". Can anyone explain why this happens?

SELECT
    ANS.ID,
    ANS.SURNAME,
    ANS.GIVENNAMES,
    A.EMPLOYERNUMBER,
    A.CLASSIFICATION,
    ANS.PENSIONNRA
FROM
    ANNUALSTATEMENTS ANS,
    (SELECT
         ES.ID,
         ES.EMPLOYERNUMBER,
         ES.CLASSIFICATION,
         ES.YEARENDDATE
    FROM
         STATEMENTEMPLYRSES ES,    
         (SELECT 
              SE.ID, 
              COUNT(SE.CLASSIFICATION) TOTALOCC
         FROM 
              STATEMENTEMPLYRSES SE
         WHERE 
              SE.YEARENDDATE = TO_DATE('31/12/2008','DD/MM/YYYY')
         GROUP BY 
              SE.ID
         ) D
    WHERE
         ES.ID = D.ID
         AND D.TOTALOCC = 1
         AND ES.CLASSIFICATION NOT IN ('Full-Time','Part-Time','FULL TIME','PART TIME')
         AND ES.YEARENDDATE = TO_DATE('31/12/2008','DD/MM/YYYY')
    ) A
    
WHERE
    ANS.ID = A.ID
    AND ANS.YEARENDDATE = TO_DATE('31/12/2008','DD/MM/YYYY')
    AND ANS.PENSIONNRA > 0
    AND EXISTS (SELECT 1
            FROM V3MEMBERSTATUS VMS
            WHERE VMS.STATUSDATE = (SELECT MAX(STATUSDATE) FROM V3MEMBERSTATUS  WHERE ID = VMS.ID AND V3CAREERCREATEDATE = VMS.V3CAREERCREATEDATE)
            AND VMS.TRANSDATE = (SELECT MAX(TRANSDATE) FROM V3MEMBERSTATUS WHERE ID = VMS.ID AND V3CAREERCREATEDATE = VMS.V3CAREERCREATEDATE AND STATUSDATE = VMS.STATUSDATE)
            AND VMS.STATUSCODE IN ('AC', 'DS')
            AND VMS.ID = ANS.ID
            AND VMS.V3CAREERCREATEDATE = ANS.V3CAREERCREATEDATE) --active members 
ORDER BY
    ANS.ID

                                  
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Asked On
2009-10-07 at 13:07:27ID24793831
Tags

oracle

,

pl/sql

Topics

PL / SQL

,

Oracle 9.x

Participating Experts
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Comments
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Answers

 

by: HainKurtPosted on 2009-10-07 at 13:32:10ID: 25519723

intead of

SELECT *
FROM
    ANNUALSTATEMENTS ANS,
    (...) A
WHERE
...
    AND EXISTS (...) --active members
ORDER BY
    ANS.ID
   
    you can use following structure, which I believe it will improve performance... and after that, you can rebuild all indexes on related tables... some indexes may be corrupt (it happened to me a while ago)

SELECT * 
FROM
    ANNUALSTATEMENTS ANS,
    (...) A,
    (...) M --active members 
WHERE
...
    AND M.ID = ANS.ID
ORDER BY
    ANS.ID  

                                              
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by: shepp_itPosted on 2009-10-07 at 13:46:26ID: 25519866

Hello HainKurt,

I tried your logic but it doesn't resolve the problem... I don't believe it is supposed to improve performance either, because actually ANNUALSTATEMENTS is a quite a large table...

I had the same problem a while ago when I used the similar logic you provided... and by using "exists" keywords i was able to fix it. I really wonder what is the cause of this problem, since it only happens when I excute the select statement within a cursor like "select cursor (<above code>)mycur from dual"... Any other suggestion/advice would be appreciated!

 

by: HainKurtPosted on 2009-10-07 at 13:52:02ID: 25519925

"screen hangs" means how? when you open it, or loop?
maybe you are not fetching the next record? can you show the code how you use this in cursor and manupulate?

 

by: shepp_itPosted on 2009-10-07 at 13:59:31ID: 25519999

I mean the query never stops executing. Below code is the complete code I ran on pl/sql. It's really nothing more or less than this:
select cursor(
... what i posted earlier goes here
)mycur
from dual

Above code should work with no problem just as
select cursor(
select * from tableA
)mycur
from dual
where imycur cursor will store the same information tableA has.

select
    cursor
         (SELECT
              ANS.ID,
              ANS.SURNAME,
              ANS.GIVENNAMES,
              A.EMPLOYERNUMBER,
              A.CLASSIFICATION,
              ANS.PENSIONNRA
         FROM
              ANNUALSTATEMENTS ANS,
              (SELECT
                   ES.ID,
                   ES.EMPLOYERNUMBER,
                   ES.CLASSIFICATION,
                   ES.YEARENDDATE
              FROM
                   STATEMENTEMPLYRSES ES,    
                   (SELECT 
                        SE.ID, 
                        COUNT(SE.CLASSIFICATION) TOTALOCC
                   FROM 
                        STATEMENTEMPLYRSES SE
                   WHERE 
                        SE.YEARENDDATE = TO_DATE('31/12/2008','DD/MM/YYYY')
                   GROUP BY 
                        SE.ID
                   ) D
              WHERE
                   ES.ID = D.ID
                   AND D.TOTALOCC = 1
                   AND ES.CLASSIFICATION NOT IN ('Full-Time','Part-Time','FULL TIME','PART TIME')
                   AND ES.YEARENDDATE = TO_DATE('31/12/2008','DD/MM/YYYY')
              ) A
              
         WHERE
              ANS.ID = A.ID
              AND ANS.YEARENDDATE = TO_DATE('31/12/2008','DD/MM/YYYY')
              AND ANS.PENSIONNRA > 0
              AND EXISTS (SELECT 1
                      FROM V3MEMBERSTATUS VMS
                      WHERE VMS.STATUSDATE = (SELECT MAX(STATUSDATE) FROM V3MEMBERSTATUS  WHERE ID = VMS.ID AND V3CAREERCREATEDATE = VMS.V3CAREERCREATEDATE)
                      AND VMS.TRANSDATE = (SELECT MAX(TRANSDATE) FROM V3MEMBERSTATUS WHERE ID = VMS.ID AND V3CAREERCREATEDATE = VMS.V3CAREERCREATEDATE AND STATUSDATE = VMS.STATUSDATE)
                      AND VMS.STATUSCODE IN ('AC', 'DS')
                      AND VMS.ID = ANS.ID
                      AND VMS.V3CAREERCREATEDATE = ANS.V3CAREERCREATEDATE) --active members 
         ORDER BY
              ANS.ID    
	)mycur
from
	dual

                                              
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by: HainKurtPosted on 2009-10-07 at 14:06:46ID: 25520088

I could not get how and why do you need such structure

select cursor(...) mycur from dual

use

open mycur for (...)

or

cursor mycursor is (...)
open mycursor

 

by: HainKurtPosted on 2009-10-07 at 14:09:25ID: 25520114

maybe you are trying to something like this

select h.*, cursor (...) myCur from HugeTable h

which will create one cursor for each record, and you may not have enough resources for this operation...

 

by: shepp_itPosted on 2009-10-07 at 14:45:33ID: 25520439

We need this structure because we want to generate xml in such format:
< mycur >
    < rec1 >something< /rec1 >
    ...
< /mycur >
< mycur2 >
...
< /mycur2 >
...
and the tool we use make this possible by executing select cursor(...)c1, cursor(...)c2 from dual. This tool works pretty much the same as Oracle's XML SQL Utility (XSU). I don't think there is a problem with the way we execute the select statement.
And i'm not trying to do something like select h.*, cursor (...) myCur from HugeTable h, but all l I'm doing is executing select cursor(...)mycur from dual at this time, which really is the code i posted...

 

by: shepp_itPosted on 2009-10-07 at 14:57:16ID: 25520520

I found out what the problem is.

I had code:
SELECT *
FROM
    ANNUALSTATEMENTS ANS,
    (...) A
WHERE
    ANS.ID = A.ID
    AND EXISTS (select 1... where id = ANS.ID)

I don't know why, but I had to add the restriction "ID=A.ID" at the EXISTS statement:
AND EXISTS (select 1... where id = ANS.ID and ID=A.ID)
even though I already linked ANS.ID=A.ID in previous line... dunno why but it solved the problem!

 

by: HainKurtPosted on 2009-10-08 at 16:34:02ID: 25531310

strange, does not make any sense... you should check the execution plan without use of that addition... maybe adding that forces use of some indexes...

20120131-EE-VQP-002

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