[NOVICE] Using set role inside a function question

Hi All,

                I have a function pass in a user login id (p_runas_id) and the it will insert a row into a table after that set role to that pass in id.   This function complied fine but getting ERROR:  role "p_runas_id" does not exist CONTEXT:  SQL statement "SET ROLE p_runas_id" when execute.  Any suggestion?

Thank you very much,

Garry

CREATE OR REPLACE FUNCTION set_netid_context(p_runas_id       varchar(30))

RETURNS void

AS $$

Declare

     v_dm_name                    varchar(30);

     v_runid                                             varchar(30);

     v_ora_id               numeric;

BEGIN

      INSERT INTO obiee_context_audit(context_date, ora_sid, db_user, runas_id)

   VALUES (now(), pg_backend_pid(), SESSION_USER, p_runas_id);

      SET ROLE p_runas_id;

END; $$

LANGUAGE plpgsql;