Date: Sat, 10 Dec 2011 17:17:25 +0100
From: Andreas Kretschmer <akretschmer@spamfence.net>
To: pgsql-sql@postgresql.org
Subject: Re: conditional FROM
Message-ID: <20111210161725.GA15506@tux>
References: <20111210170332479879.3df30525@klingler.net>
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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...

I think, you can't do that, you have to build your query and execute
that string. You should use a function to do that.


Andreas
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