• Subject: Re: SQL Existence Check
  • From: "Walden Leverich" <walden@xxxxxxxxxxxxxxx>
  • Date: Tue, 18 Nov 1997 18:54:06 -0500

Good idea. If I declare the cursor as "optimize for 1 record" then I may
even see this perform in a decent manner. Hopefully, if I select only key
fields DB2/SMP will see that this can be accomplished with index covering
and I will never even hit the physical.

-Walden
-----Original Message-----
From: Vern Hamberg <hambergv@goldengate.net>
To: MIDRANGE-L@midrange.com <MIDRANGE-L@midrange.com>
Cc: walden@techsoftinc.com <walden@techsoftinc.com>
Date: Tuesday, November 18, 1997 5:33 PM
Subject: Re: SQL Existence Check


>Walden
>
>At 12:23 PM 11/14/97 -0500, you wrote:
>>I would like to check for the existence of a record in a file using SQL.
>>There could be 0, 1 or more than 1 records that match the selection
>>criteria, I only care if records exist, not how many.
>>
>>I know that SQL has the EXISTS predicate, but I cannot use it by itself,
it
>>must be in the where clause of a statement. I realize that I could do a
>>select count(*) where.... but this would require DB2/400 to read all the
>>matching records in order to count them. In my case as soon as DB2 finds 1
>>record it can stop looking.
>
>Is this embedded SQL? If so, FETCH and check the return code. Doesn't -100
>mean no more records?
>
>If not embedded, I'll have to think about it some more.
>
>HTH
>Vernon Hamberg
>Systems Software Programmer
>Old Republic National Title Insurance Company
>400 Second Avenue South
>Minneapolis, MN 55401
>(612) 371-1111 x480
>


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