My very first PL/pgSQL procedure...

Hi,

I've got a problem with my very first PL/pgSQL procedure !
I created the following procedure, that should reconfigure a sequence :
---------------------------------------------------------------------------------------------------------------------

CREATE OR REPLACE FUNCTION seq_min(sequence_name varchar, minval
integer) RETURNS VOID AS $$
DECLARE
current_seq integer;
BEGIN
LOCK TABLE sequence_name IN ACCESS EXCLUSIVE MODE;
current_seq := last_value FROM sequence_name;
IF current_seq < minval THEN
ALTER SEQUENCE sequence_name RESTART WITH minval;
END IF;
END;
$$ LANGUAGE plpgsql;
---------------------------------------------------------------------------------------------------------------------

I call it from the psql interface by :
SELECT seq_min('seq_mytable', 1029);

But PostgreSQL returns the following error (translated from french) :

ERROR: syntax error on or near «$1» at character 13
QUERY : LOCK TABLE $1 IN ACCESS EXCLUSIVE MODE
CONTEXT : PL/pgSQL function "seq_min" line 4 at SQL statement
LINE 1 : LOCK TABLE $1 IN ACCESS EXCLUSIVE MODE

So it seems that PostgreSQL have troubles handling my variable
"sequence_name"...
Any idea ?

Thank you in advance,
Philippe Ferreira, France.