Oracle 18c

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
CREATE TABLE EMPLOYEES (
    ID       NUMBER PRIMARY KEY,
    SALARY   NUMBER
);
CREATE TABLE BONUS (
    ID         NUMBER
        REFERENCES EMPLOYEES ( ID ),
    INCREASE   NUMBER,
    TOTAL      NUMBER
);
CREATE OR REPLACE TRIGGER TRG_EMPLOYEES AFTER
    UPDATE OF SALARY ON EMPLOYEES
    FOR EACH ROW
BEGIN
    UPDATE BONUS
    SET
        TOTAL = :NEW.SALARY + INCREASE
    WHERE
        ID = :NEW.ID;

END;
/
CREATE OR REPLACE TRIGGER TRG_BONUS BEFORE
    INSERT OR UPDATE OF INCREASE ON BONUS
    FOR EACH ROW
DECLARE
    LV_TOTAL   BONUS.TOTAL%TYPE;
BEGIN
    SELECT
        SALARY + NVL(:NEW.INCREASE, 0)
    INTO LV_TOTAL
    FROM
        EMPLOYEES
    WHERE
        ID = :NEW.ID;

    :NEW.TOTAL := LV_TOTAL;
END;
/
INSERT INTO EMPLOYEES VALUES (1, 1000);
1 rows affected

SELECT * FROM EMPLOYEES;


ID
SALARY


1
1000


INSERT INTO BONUS (ID, INCREASE) VALUES (1, 234)
1 rows affected

SELECT * FROM BONUS;


ID
INCREASE
TOTAL


1
234
1234