MERGE different queries

CREATE TABLE employee
(
employee_id NUMBER(5),
first_name  VARCHAR2(20),
last_name   VARCHAR2(20),
dept_no     NUMBER(2),
salary      NUMBER(10)
);

INSERT INTO employee VALUES (1, 'Dan', 'Morgan', 10, 100000);
INSERT INTO employee VALUES (2, 'Jack', 'Cline', 20, 100000);
INSERT INTO employee VALUES (3, 'Elizabeth', 'Scott', 20, 50000);
INSERT INTO employee VALUES (4, 'Jackie', 'Stough', 20, 40000);
INSERT INTO employee VALUES (5, 'Richard', 'Foote', 20, 30000);
INSERT INTO employee VALUES (6, 'Joe', 'Johnson', 20, 70000);
INSERT INTO employee VALUES (7, 'Clark', 'Urling', 20, 90000);
COMMIT;

CREATE TABLE bonuses
(
employee_id NUMBER,
bonus NUMBER DEFAULT 100
);

INSERT INTO bonuses (employee_id) VALUES (1);
INSERT INTO bonuses (employee_id) VALUES (2);
INSERT INTO bonuses (employee_id) VALUES (4);
INSERT INTO bonuses (employee_id) VALUES (6);
INSERT INTO bonuses (employee_id) VALUES (7);
COMMIT;

MERGE INTO bonuses B
USING (
  SELECT employee_id, salary
  FROM employee
  WHERE dept_no =20) E
ON (B.employee_id = E.employee_id)
WHEN MATCHED THEN
  UPDATE SET B.bonus = E.salary * 0.1
WHEN NOT MATCHED THEN
  INSERT (B.employee_id, B.bonus)
  VALUES (E.employee_id, E.salary * 0.05);


I hope you all have enjoyed reading this article. Comments are welcome....