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Prob with ORDER BY switching from a CURSOR to Single-Select

 
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Melwyn Mark DSouza

New User


Joined: 02 Jun 2009
Posts: 2
Location: India

PostPosted: Tue Jun 02, 2009 3:23 pm    Post subject: Prob with ORDER BY switching from a CURSOR to Single-Select
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Hi,

I have a cursor declared as follows:

Code:

SELECT A.COL1,
       A.EFF_DT,
       A.END_DT
  FROM  TABLEA A
WHERE A.COL1='X'
    AND A.COL2 ='Y'
ORDER BY END_DT DESC



I am required to improve the performance of this query. Also, in the code it so happens that only the first row retrieved is required. So I tried the following in a single-select statement:
Code:

SELECT A.COL1,
       A.EFF_DT,
       A.END_DT
  FROM  TABLEA A
WHERE A.COL1='X'
    AND A.COL2 ='Y'
ORDER BY END_DT DESC
FETCH FIRST 1 ROW ONLY



But now the PROBLEM is that the first row retrieved is not the same.

There is a non-unique index on COL1. Primary key is composite of several columns, none of which are used in this query.

I have even tried using MAX in query and sub-query but to no avail.

Any pointers?

Thanks & Regards,
Melwyn
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dbzTHEdinosauer

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Joined: 20 Oct 2006
Posts: 6966
Location: porcelain throne

PostPosted: Tue Jun 02, 2009 3:55 pm    Post subject:
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Well either upgrade to version 8, where you can have an ORDER BY in a singleton select

or

go back to the CURSOR
use OPTIMIZE for 1 ROW.
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Melwyn Mark DSouza

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Joined: 02 Jun 2009
Posts: 2
Location: India

PostPosted: Tue Jun 02, 2009 4:05 pm    Post subject:
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Thanks Dick.

In DB2 Platinum I see

DB2 VERSION :V9R1M0

Thanks & Regards,
Melwyn
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