how to create a multi columns return function ?

Hi

I'm moving databases from sybase to postgres.
But I have difficulties in creating a postgres equivalent to the sybase
stored procedures...

Apparently, Postgres functions should work, but the syb stored procedures
get only one parameter and return several colums

Here's the code I wrote in postgresql :

create function function_name( int ) returns text
AS ' SELECT column1, column2, column3,...,column15
FROM table_name
WHERE colum1 = $1 AND column5 = \'specific value\' AND column8 =
\'specific_value2 \' '
LANGUAGE 'SQL';

and I get the message error : returns multi columns

I'm wondering too if It's possible to create a view with a parameter if
functions don't work.

Has anybody faced the same problem ?

I need help

thanks