plpgsql syntax error

Hi,

I'm beginner in postgresql and plpgsql and i have the following problem.
I'm trying to check a table if exists or not and when not exists then
create it, but I get a syntax error.

Here is my code:


create or replace function check_table() returns void as
$$

DECLARE

mmonth integer;
yyear integer;

tblname varchar(30);

begin

SELECT into mmonth EXTRACT(MONTH FROM TIMESTAMP 'now' - INTERVAL '1 MONTH');
SELECT into yyear EXTRACT(YEAR FROM TIMESTAMP 'now' - INTERVAL '1 MONTH');

tblname := 'tbl_' || yyear || mmonth;


    if not exists(select * from information_schema.tables
        where
            table_catalog = CURRENT_CATALOG and table_schema = CURRENT_SCHEMA
            and table_name = tblname) then

        create table tblname
        (

        );

    end if;

end;
$$
language 'plpgsql';



But I get the following error:

ERROR:  syntax error at or near "$1"
LINE 1: create table  $1  ( )
                      ^
QUERY:  create table  $1  ( )
CONTEXT:  SQL statement in PL/PgSQL function "check_table" near line 22


Thanks!