Иерархия в FireBird 1.5

ALTER PROCEDURE EXPAND (AnID VARCHAR(32), Self INTEGER)
  RETURNS (ID VARCHAR(32), PARENT_ID VARCHAR(32), TREE_LEVEL INTEGER)
AS
BEGIN
  TREE_LEVEL = 0;
  IF (:Self <> 0) THEN
  BEGIN
    ID = :AnID;
    SUSPEND;
  END


  FOR SELECT KOD_SUBUSER, :AnID FROM STRUCT_USERS
  WHERE KOD_USER = :AnID INTO :ID, :PARENT_ID
    DO FOR SELECT ID, :PARENT_ID, TREE_LEVEL+1 FROM EXPAND (:ID, 1) INTO :ID, :PARENT_ID, :TREE_LEVEL
      DO SUSPEND;
END;