EXECUTE BLOCK
RETURNS (
    RNAME CHAR(31))
AS
  DECLARE C CURSOR FOR (
      SELECT
          RDB$RELATION_NAME
      FROM RDB$RELATIONS
      ORDER BY RDB$RELATION_NAME);
  DECLARE C_FLAG BOOLEAN = TRUE;
BEGIN
  OPEN C;
  WHILE (C_FLAG) DO
  BEGIN
    FETCH C
    INTO :RNAME;
    C_FLAG = (ROW_COUNT <> 0);
    IF (C_FLAG) THEN
    BEGIN
      -- тут куча обработки
      SUSPEND;
    END
  END
  CLOSE C;
END

EXECUTE BLOCK
RETURNS (
  o CHAR(31))
AS
BEGIN
  FOR
    SELECT
      rdb$relation_name AS name
    FROM
      rdb$relations AS CURSOR c
  DO
  BEGIN
    o = c.name;
    SUSPEND;
  END
END

EXECUTE BLOCK
RETURNS (
  N INT,
  RNAME CHAR(31))
AS
  DECLARE C SCROLL CURSOR FOR (
    SELECT
      ROW_NUMBER() OVER(ORDER BY RDB$RELATION_NAME) AS N,
      RDB$RELATION_NAME
    FROM RDB$RELATIONS
    ORDER BY RDB$RELATION_NAME);
BEGIN
  OPEN C;
  -- перемещаемся на первую запись (N=1)
  FETCH FIRST FROM C;
  RNAME = C.RDB$RELATION_NAME;
  N = C.N;
  SUSPEND;
  -- перемещаемся на 1 запись вперёд (N=2)
  FETCH NEXT FROM C;
  RNAME = C.RDB$RELATION_NAME;
  N = C.N;
  SUSPEND;
  -- перемещаемся на пятую запись (N=5)
  FETCH ABSOLUTE 5 FROM C;
  RNAME = C.RDB$RELATION_NAME;
  N = C.N;
  SUSPEND;
  -- перемещаемся на 1 запись назад (N=4)
  FETCH PRIOR FROM C;
  RNAME = C.RDB$RELATION_NAME;
  N = C.N;
  SUSPEND;
  -- перемещаемся на 3 записи вперёд (N=7)
  FETCH RELATIVE 3 FROM C;
  RNAME = C.RDB$RELATION_NAME;
  N = C.N;
  SUSPEND;
  -- перемещаемся на 5 записей назад (N=2)
  FETCH RELATIVE -5 FROM C;
  RNAME = C.RDB$RELATION_NAME;
  N = C.N;
  SUSPEND;
  -- перемещаемся на первую запись (N=1)
  FETCH FIRST FROM C;
  RNAME = C.RDB$RELATION_NAME;
  N = C.N;
  SUSPEND;
  -- перемещаемся на последнюю запись
  FETCH LAST FROM C;
  RNAME = C.RDB$RELATION_NAME;
  N = C.N;
  SUSPEND;
  CLOSE C;
END