To: pgsql-sql@postgresql.org
From: Harald Fuchs <hari.fuchs@gmail.com>
Subject: Re: Is there any function to test for numeric ips?
Date: Fri, 11 Dec 2009 17:23:47 +0100
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References: <E94D918326D044C69895D829038E31B2@marktestcr.marktest.pt>
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In article <E94D918326D044C69895D829038E31B2@marktestcr.marktest.pt>,
"Oliveiros C," <oliveiros.cristina@marktest.pt> writes:

> Dear All,
> I have a table with host names and some happen to be numeric IPs.
 
> I would like to be able to filter out the later.
 
> Is there any function pre-defined in the system that can test a particular text
> type value to see if it is a numeric ip?
 
> Something that returns true if applied to '192.168.1.1' but false if applied to
> 'videos.sapo.pt' ?
 
> I considered NOT LIKE '%.%.%.%' but I'm affraid it will filter out host names
> like 'www.google.com.br'
 
> I've realized that, for ex, inet 'x.x.x.x' will fail if the input is not a
> numeric IP,
> is there any simple and direct way to somewhat trap that error and convert it
> to a false value that can be used
> in a WHERE clause?

You could use a regular expression match:

  SELECT host
  FROM t1
  WHERE host ~ '^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$'