From: David Johnston <polobo@yahoo.com>
To: Richard Klingler <richard@klingler.net>
Cc: pgsql-sql@postgresql.org <pgsql-sql@postgresql.org>
Subject: Re: conditional FROM
Date: Sat, 10 Dec 2011 11:28:29 -0500
Message-ID: <2BBB44CA-7EFA-4084-906F-6CB72AD28C6E@yahoo.com> (raw)
In-Reply-To: <20111210170332479879.3df30525@klingler.net>
References: <20111210170332479879.3df30525@klingler.net>
On Dec 10, 2011, at 11:03, Richard Klingler <richard@klingler.net> wrote:
> Good day...
>
> I'm trying to build a query for PGSQL 9.1 where a table has two
> references with only one being used depending of the type of entry..
>
> For example, the table has following simplified structure:
>
> portid primary key
> port2node index to table node
> port2card index to table card
>
> So how can I do a conditional FROM clause in the query depending on the
> column port2node and port2card?
> If port2card is Null or 0 I don't want it in the FROM clause as the
> query will return unneccessary duplicate
> row...the same goes for port2node being Null or 0...
>
>
> thanx in advance
> richard
>
>
Two options (one of which may not work for you).
1. Write two queries, one for each table, and union the results.
2. Use LEFT JOINs (somehow...)
David J.
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: polobo@yahoo.com, richard@klingler.net
Subject: Re: conditional FROM
In-Reply-To: <2BBB44CA-7EFA-4084-906F-6CB72AD28C6E@yahoo.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox