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From: Arkin <arkin@exoffice.com>
To: Peter Mount <petermount@it.maidstone.gov.uk>
Cc: 'Guillaume Rousse' <Guillaume.Rousse@univ-reunion.fr>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: Is this usage correct ?
Date: Wed, 19 Apr 2000 13:11:02 -0700
Message-ID: <38FE12D6.B4274285@exoffice.com> (raw)
References: <1B3D5E532D18D311861A00600865478C70C4D0@exchange1.nt.maidstone.gov.uk>

Most RDBMS support two modes of queries. Statements and prepared
statements.

Statements are SQL strings that are parsed and processed in one go.
Prepared statements are pre-prepared and can be reused any number of
times. Since parameters tend to change across method invocation, they
support bound parameters (the '?' thingy).

In terms of performance statements are slightly faster if used only once
(Oracle 7) and prepared statements are way faster if used twice or more
times (Oracle 7 again). The RDMBS will construct a query plan during
preperation and only once for a given statement, thus saving a
non-marginal cost (especially if the query is rather complex). In fact,
in some instances where the results of a query are less than 100 records
(w/o long binary/char fields), using prepared statement can achive an
80% performance improvement.

arkin



Peter Mount wrote:
> 
> In theory it would be ok, but as PreparedStatement extends Statement,
> why cause the extra overhead and just use Statement?
> 
> Peter
> 
> --
> Peter Mount
> Enterprise Support
> Maidstone Borough Council
> Any views stated are my own, and not those of Maidstone Borough Council.
> 
> -----Original Message-----
> From: Guillaume Rousse [mailto:Guillaume.Rousse@univ-reunion.fr]
> Sent: Wednesday, April 19, 2000 10:47 AM
> To: pgsql-interfaces@postgresql.org
> Subject: [INTERFACES] Is this usage correct ?
> 
> Is it correct to use a preparedStatement with no variable element, as
> this:
> PreparedStatement stmp=conn.prepareStatement("delete from table where
> oid="+oid);
> stmt.excuteUpdate();
> 
> Or is it mandatory to use :
> PreparedStatement stmp=conn.prepareStatement("delete from table where
> oid=?");
> stmt.setInt(1,oid);
> stmt.excuteUpdate();
> 
>  --
> Guillaume Rousse
> Iremia - Université de la Réunion
> 
> Sleep doesn't exists. Just lack of cafeine.

-- 
----------------------------------------------------------------------
Assaf Arkin                                           www.exoffice.com
CTO, Exoffice Technologies, Inc.                        www.exolab.org



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