From: Gregory Stark <stark@enterprisedb.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Meskes <meskes@postgresql.org>
Cc: PostgreSQL Interfaces <pgsql-interfaces@postgresql.org>
Subject: Re: PQprepare question
Date: Fri, 11 May 2007 14:32:22 +0100
Message-ID: <87ps571o61.fsf@oxford.xeocode.com> (raw)
In-Reply-To: <17526.1178888881@sss.pgh.pa.us>
References: <20070511111647.GA18711@feivel.credativ.de>
<17526.1178888881@sss.pgh.pa.us>
"Tom Lane" <tgl@sss.pgh.pa.us> writes:
> Michael Meskes <meskes@postgresql.org> writes:
>> According to the docs parameters are referenced as $1, $2, and so. Is
>> there a reason not to use "?" as placeholder?
>
> It's an operator name.
Most drivers such as JDBC and DBD::Pg do allow you to use ? parameters because
they're the ODBC standard. But they're just replacing them with $1 and so on
behind your back. If you want your code to be portable to other databases then
it makes sense to use ?
But otherwise there are a few advantages to using $1, $2... a) You can change
your query to possibly use the arguments in a different order without having
to change the execute parameters as well. b) You can use a parameter multiple
times in a query without having to burden your execute call site with multiple
copies of the parameter.
I think you lose if you have an operator ? and want to use these drivers
though. Even if you only use $n parameters the driver may still get confused.
(At the very least if you ever have a query with no parameters and a ?
operator in it).
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
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To: pgsql-interfaces@postgresql.org
Cc: stark@enterprisedb.com, tgl@sss.pgh.pa.us, meskes@postgresql.org
Subject: Re: PQprepare question
In-Reply-To: <87ps571o61.fsf@oxford.xeocode.com>
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