Re: sql Vs RLA to test existance

[Luis Rodriguez <luisro58@xxxxxxxxx>]

David,

IIRC, EXISTS stops as soon as it finds the first record. The syntax is:

SELECT *  FROM TABLE1  WHERE EXISTS(SELECT 1 FROM TABLE2 WHERE TABLE1.FIELD
= TABLE2.FIELD) ;

Regards,
Luis Rodriguez
IBM Certified Systems Expert — eServer i5 iSeries
--



On Tue, Feb 15, 2011 at 10:14 AM, David FOXWELL <David.FOXWELL@xxxxxxxxx>wrote:

> Hi,
>
> I need to find if a transaction of a particular type and amount exists for
> a client.
>
> I cannot remember how to apply the SQL Exists( ) to look for the
> transaction.
>
> Select '1' from ???? where exists ( select * from mytable where myfield =
> 'myfield')
>
>
> Then again, I seem to remember that EXists will scan all the rows and not
> just stop at the first one that satisfies the search criteria as I could do
> with RLA.
>
> Can someone put me straight please?
>
> Thanks.
>
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