Oracle date比较大小

-- Created on 2010/04/17 by NAN
declare
  -- Local variables here
  i integer;
  v_date1 DATE;
  v_date2 DATE;
begin
  -- Test statements here
  v_date1 := SYSDATE;
  v_date2 := to_date( '2008-09-08');
  IF v_date1 > v_date2 THEN
     dbms_output.put_line( 'if');  
  ELSE
     dbms_output.put_line( 'else');
  END IF;
end;