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RE: tuning query with concat string.

From: Igor Neyman <ineyman_at_perceptron.com>
Date: Tue, 21 Mar 2006 11:02:40 -0500
Message-ID: <F4C27E77F7A33E4CA98C19A9DC6722A2C4CB4E@EXCHANGE.corp.perceptron.com>


Why would you want to re-write it?

This concatenation on the right side of

ws_id = 'S'||userenv('SESSIONID')

doesn't prevent from using index on "ws_id" (if there is one, and that's your concern).

Of cource, it'd be different story, if it would be the other way around, i.e.:

Ws_id || 'S' = userenv('SESSIONID')

Igor

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of The Human Fly Sent: Tuesday, March 21, 2006 10:37 AM
To: Wolfgang Breitling
Cc: oracle-l
Subject: Re: tuning query with concat string.

I think my question was littble confused.

Okay, following is the query that I wanted to write,

select max(start_time) from fm_audit_form where ws_id = 'S'||userenv('SESSIONID')

Is there any way that I can rewrite this query?

Long time ago, I have read that we can rewrite queries that has concat in the where clause values.

On 3/21/06, Wolfgang Breitling <breitliw_at_centrexcc.com> wrote:
> SELECT ...... FROM where COLUMN = 'SVALUE2';
>
> :-)
>
> Quoting The Human Fly <sjaffarhussain_at_gmail.com>:
>
> > How can I rewrite the query which uses concatination in the where
> > clause? For an example,
> >
> > SELECT ...... FROM where COLUMN = 'S'||'VALUE2';
> >
> --
> regards
>
> Wolfgang Breitling
> Oracle 7,8,8i,9i OCP DBA
> Centrex Consulting Corporation
> www.centrexcc.com
>
>

--
Best Regards,
Syed Jaffar Hussain
8i,9i & 10g, OCP DBA
Banque Saudi Fransi,
Saudi Arabia
http://jaffardba.blogspot.com/
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Received on Tue Mar 21 2006 - 10:02:40 CST

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