CREATE PROCEDURE DT2STR (
    DT DATE)
RETURNS (
    STR VARCHAR( 10 ))
AS
  declare variable tmp integer;
begin
  tmp=extract(day from dt);
  if (tmp< 10 ) then
    str='0'||tmp;
  else
    str=tmp;
  str=str||'.';
  tmp=extract(month from dt);
  if (tmp< 10 ) then
    str=str||'0'||tmp;
  else
    str=str||tmp;
  str=str||'.'||extract(year from dt);
  suspend;
end

select
  'дата - '||(select str from dt2str('01.01.2004'))
from
  rdb$database

SELECT
  DOGOVORS.DL_NO ||' от '||(select str from dt2str(DOGOVORS.DATESTART)) AS NUMDATE
FROM
  DOGOVORS