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Date: Sat, 10 Dec 2011 17:03:32 +0100
From: Richard Klingler <richard@klingler.net>
To: pgsql-sql@postgresql.org
Message-ID: <20111210170332479879.3df30525@klingler.net>
Subject: conditional FROM
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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