Re: psql can't subtract

On 03/25/2011 10:59 AM, hubert depesz lubaczewski wrote:
> On Fri, Mar 25, 2011 at 09:29:57AM -0600, Rob Sargent wrote:
>> Running 9.0.3 (client and server)
>>
>>
>> Seems I cannot subtract 1 from the result of position.
>>
>> select distinct
>>         substring( substring(xml_text,1,300),
>>                    position( 'xmlns=' in substring(xml_text,1,300)) +
>> length('xmlns="'),
>>                    position( '"' in (substring(substring(xml_text,1,300),
>>                                                 position( 'xmlns=' in
>> substring(xml_text,1,300)) + length('xmlns="'),
>>                                                 100)))
>>                    ) as namespace
>> from elements;
>
> is there any particular reason why you're writing something that
> complicated instead of using simple regexp?
>
> select distinct regexp_replace( xml_text, '.*xmlns="([^"]+)".*', E'\\1') from elements;
>
> Best regards,
>
> depesz
>

Just gross incompetency with regexps. Much thanks.