> if D.SuplCde is 'ABC' and ISupplierCode is NULL, result will be

TRUE??

Wrong. Since one has a value and the other is NULL, they are DISTINCT.
The NOT would flip that to false.

-----Original Message-----
From: firebird-support@yahoogroups.com
[mailto:firebird-support@yahoogroups.com] On Behalf Of Maya Opperman
Sent: Thursday, May 15, 2008 11:28 AM
To: firebird-support@yahoogroups.com
Subject: RE: [firebird-support] Re: Possible to write this in a way that
indices will be used

>Doru wrote:>
>If you are using Firebird 2+ Testing DISTINCTness will be a nice way to

>go :
>http://www.firebirdsql.org/manual/nullguide-langelem.html

OK, so ((D.SuplCde = :ISupplierCode) or (:ISupplierCode is null))

would change to ((D.SuplCde is not distinct from :ISupplierCode))

to achieve the same results?

Ie. if D.SuplCde is 'ABC' and ISupplierCode is 'ABC', result will be
TRUE.
if D.SuplCde is 'ABC' and ISupplierCode is NULL, result will be
TRUE??
if D.SuplCde is 'ABC' and ISupplierCode is 'XYZ', result will be
FALSE.

Is that right?

Thanks
Maya

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