Message-Id: <5.2.1.1.0.20040430121848.02a4cda0@pop6.sympatico.ca>
Date: Fri, 30 Apr 2004 12:24:03 -0400
To: <pgsql-sql@postgresql.org>
From: Frank Bax <fbax@sympatico.ca>
Subject: Re: isnumeric() function?
In-Reply-To: <003601c42ec7$e7806ee0$8401a8c0@home.axiontech.com>
References: <20040430141145.40776.qmail@web20809.mail.yahoo.com>
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At 11:29 AM 4/30/04, Yudie wrote:
>Great the function works, but what does it means?
>SELECT $1 ~ ''^[0-9]+$''
>
>Yudie


The ~ is a pattern matching operator.
         ^ matches beginning of string
         [0-9] matches any numeric digit 0 thru 9.
         + matches one or more occurrences of what came before (digits in 
this case)
         $ matches end of string
The ^ and $ are important - if they were left out, the pattern would match 
a string containing both numeric and non-numeric data.

You can change the + to * if you decide that an empty string should be 
considered numeric.

Frank