Re: POSIX RE starting with a (

On Wed, 2004-08-11 at 14:39, Nick Barr wrote:
> Hi,
>
> Just noticed something funny with the POSIX Regular expressions and
> wondered if it is a bug, or whether I am doing something wrong. I am
> using the POSIX RE in a function that is used in several places so would
> have to put some nasty if statement in there for this side case if there
> is not work around.
>
> ======================================================================
> intranet=# select track_id, track_name from ms_track where track_name
> like '(%';
> track_id | track_name
> ----------+---------------------------------
> 1294 | (I Can''t Get No) Satisfaction
> 1340 | (Hidden Track)
> 1503 | (Nice Dream)
> 1942 | (I) Get Lost
> (4 rows)
>
> intranet=# select track_name from ms_track where track_name ~ '^\(';
> ERROR: invalid regular expression: parentheses () not balanced
> intranet=# select track_name from ms_track where track_name ~ '^(';
> ERROR: invalid regular expression: parentheses () not balanced
> intranet=# select track_name from ms_track where track_name ~ '^\(';
> ERROR: invalid regular expression: parentheses () not balanced
> ======================================================================
>
> Now I have tried a similar query using the PHP POSIX Regular Expressions
> and it accepts the sequence '^\(' and matches correctly. Is this a
> "feature" of PG that cannot be worked around easily?

You need to escape the backslash:

select track_name from ms_track where track_name ~ '^\\
(';
--
Oliver Elphick olly(at)lfix(dot)co(dot)uk
Isle of Wight http://www.lfix.co.uk/oliver
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