[SQL] A function to count all ocurrences of a character within a string.
Hello pgsql community, Is there any string function (other than regex / scan & compare loop) to obtain a list (or even a count) of characters within a string? strpos and position seems to return only first occurence of a char/string within substring. The goal is to check if a string contains equal number of opening and closing parenthesis, and if there are any of them. Regards, Piotr Czekalski -- -- "TECHBAZA.PL" Sp. z o.o. Technologie WEB, eDB& eCommerce tel. (+4832) 7186081 fax. (+4832) 7003289 email: bi...@techbaza.pl -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
Re: [SQL] A function to count all ocurrences of a character within a string.
On Mon, Mar 7, 2011 at 1:20 PM, Piotr Czekalski wrote: > Hello pgsql community, > > Is there any string function (other than regex / scan & compare loop) to > obtain a list (or even a count) of characters within a string? > strpos and position seems to return only first occurence of a char/string > within substring. > The goal is to check if a string contains equal number of opening and > closing parenthesis, and if there are any of them. > > Regards, > > Piotr Czekalski Couple examples here that might help to get you started http://www.postgres.cz/index.php/PostgreSQL_SQL_Tricks#Get_count_of_substrings_in_string -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
Re: [SQL] A function to count all ocurrences of a character within a string.
On Mon, Mar 07, 2011 at 02:08:10PM -0800, bricklen wrote:
> On Mon, Mar 7, 2011 at 1:20 PM, Piotr Czekalski
> wrote:
> > Hello pgsql community,
> >
> > Is there any string function (other than regex / scan & compare loop) to
> > obtain a list (or even a count) of characters within a string?
> > strpos and position seems to return only first occurence of a char/string
> > within substring.
> > The goal is to check if a string contains equal number of opening and
> > closing parenthesis, and if there are any of them.
> >
> > Regards,
> >
> > Piotr Czekalski
>
> Couple examples here that might help to get you started
> http://www.postgres.cz/index.php/PostgreSQL_SQL_Tricks#Get_count_of_substrings_in_string
Oh, I like that trick! A little substitution and rearranging leads to:
CREATE OR REPLACE FUNCTION balanced_parens(text)
RETURNS integer AS $$
SELECT(length(replace($1, '(', '')) - length(replace($1,')',''))) ;
$$ LANGUAGE SQL IMMUTABLE;
Generalizing (curly braces? brackets?)
CREATE OR REPLACE FUNCTION balanced_pairs(text,text,text)
RETURNS integer AS $$
SELECT(length(replace($1, $2, '')) - length(replace($1,$3,''))) ;
$$ LANGUAGE SQL IMMUTABLE;
Ross
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