CREATE TABLE TEST (
    ID     INTEGER NOT NULL,
    DATA1  INTEGER,
    DATA2  INTEGER
);

INSERT INTO test ("ID") VALUES (1);

CREATE PROCEDURE SP_TEST
AS
  DECLARE VARIABLE var_id INTEGER;
BEGIN
  FOR
    SELECT
      t."ID"
    FROM
      test t
    WHERE
      t."ID" = 1
    INTO
      :var_id
    AS CURSOR
      cur_tst
  DO BEGIN
    UPDATE test t SET
      t."DATA1" = 1
    WHERE
      t."ID" = :var_id;

    UPDATE test t SET
      t."DATA2" = 2
    WHERE
      CURRENT OF cur_tst;
  END
END

    UPDATE test t SET
      t."DATA2" = 2
    WHERE
      t."ID" = :var_id;

CREATE TRIGGER TR_TEST_BU0 FOR TEST
ACTIVE BEFORE UPDATE POSITION 0
AS
  DECLARE VARIABLE var_msg VARCHAR(256);
BEGIN
  var_msg =
    'Old.Data1: ' || COALESCE(OLD."DATA1", -1) ||
    ', New.Data1: ' || COALESCE(NEW."DATA1", -1) ||
    ', Old.Data2: ' || COALESCE(OLD."DATA2", -1) ||
    ', New.Data2: ' || COALESCE(NEW."DATA2", -1);
  INSERT INTO log (
    "MSG"
  ) VALUES (
    :var_msg
  );
END