Re: SQL to only check for existence:

["rick baird" <rick.baird@xxxxxxxxx>]

Thanks Charles - very similar to Michael's answer, but with another layer.

If I get performance problems where the first match is way down in the
access path, I'll try this too.

at this point, the select without the exists() looks like a winner.

On 4/18/06, Wilt, Charles <CWilt@xxxxxxxxxxxx> wrote:
> Check out the EXISTS predicate.
>
> Select 1
> >From sysibm/sysdummy1
> Where exists (select 1 from my where myfield like '___abc___')
>
> HTH,
>
>
> Charles Wilt
> --
> iSeries Systems Administrator / Developer
> Mitsubishi Electric Automotive America
> ph: 513-573-4343
> fax: 513-398-1121
>
>
> > -----Original Message-----
> > From: rpg400-l-bounces@xxxxxxxxxxxx
> > [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of rick baird
> > Sent: Tuesday, April 18, 2006 10:56 AM
> > To: Midrange Systems Technical Discussion; RPG programming on
> > the AS400 / iSeries
> > Subject: SQL to only check for existence:
> >
> > hey all,
> >
> > Is there a way to run an SQL statement that doesn't (necessarily)
> > return anything, but only checks for the existence of one or more
> > records based on a where statement - similar to a SETLL and %found?
> >
> > I've got a rather complicated SQL statement using:
> > LIKE '___abc___'    or it could be:
> > LIKE ______xyz'
> >
> > - over a very large file, and I'm having performance issues.
> >
> > I don't want to do a count(), because I don't care how many, only that
> > at least one exists.   with count, it would have to read through the
> > entire file to determine it.
> >
> > I also tried just doing a select - optimize for 1 row and a single
> > fetch, but that seemed to take forever too.  It appears as if it is
> > searching the entire file, instead of stopping at the first one.
> >
> > help!
> >
> > Rick
> >
> > --
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