RE: SQL Existence Check

[Wiesmayr Rudolf <Rudolf.Wiesmayr@xxxxxxxxxxx>]

Hi!

There was a discussion about the 'best' way to do this in the
DB2 mailing list.

I have not yet made a compilation of the contributions.

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HTH,
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-----Original Message-----
From:   Walden Leverich [SMTP:walden@techsoftinc.com]
Sent:   Friday, November 14, 1997 6:24 PM
To:     Midrange List
Subject:        SQL Existence Check

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.

Any suggestions?

-Walden

PS. Yes, I know a single chain or setll would accomplish this. I am looking
for a SQL solution.

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