postgresql ymd() function

create or replace function ymd( p_year int, p_month int, p_day int)
returns date
language plpgsql
as $$
declare
   ret_ymd date;
begin
  SELECT TO_DATE(p_year::varchar||LPAD(p_month::varchar, 2, '0')||p_day::varchar,'YYYYMMDD')
  into ret_ymd;
  return ret_ymd;
end;$$