ALTER TABLE TBDIEF_APURACAO
ADD ID INTEGER;

CREATE SEQUENCE GTBDIEF_APURACAO;

UPDATE TBDIEF_APURACAO T SET
    T.ID = GEN_ID(GTBDIEF_APURACAO, 1)
WHERE
    T.ID IS NULL;

ALTER TABLE TBDIEF_APURACAO ALTER ID SET NOT NULL;

/* 
ALTER TABLE TBDIEF_APURACAO
ADD CONSTRAINT PK_TBDIEF_APURACAO
PRIMARY KEY (ID); 
*/

SET TERM ^ ;

CREATE OR ALTER TRIGGER TTBDIEF_APURACAO_B01I FOR TBDIEF_APURACAO
ACTIVE BEFORE INSERT POSITION 0
AS
BEGIN
  IF (NEW.ID IS NULL) THEN
    NEW.ID = GEN_ID(GTBDIEF_APURACAO, 1);
END
^

SET TERM ; ^