Triggers:

 CREATE TABLE evaluations_log (log_date DATE 
                            , action VARCHAR2(50));

evaluation is database table 

CREATE OR REPLACE TRIGGER eval_modification_trigger
  AFTER INSERT OR UPDATE OR DELETE
  ON evaluations
DECLARE log_action evaluations_log.action%TYPE;
BEGIN
  IF INSERTING THEN log_action := 'Insert';
  ELSIF UPDATING THEN log_action := 'Update';
  ELSIF DELETING THEN log_action := 'Delete';
  ELSE DBMS_OUTPUT.PUT_LINE('This code is not reachable.');
  END IF;
  INSERT INTO evaluations_log (log_date, action)
    VALUES (SYSDATE, log_action);
END;