UPSERT IN PLSQL

Question

CAN ANY ONE EXPLAIN THE UPSERT USING A PLSQL CODE(EXAMPLE)

Answer 1

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);
======================================
-- Both clauses present.
MERGE INTO test1 a USING all_objects b ON (a.object_id = b.object_id)
WHEN MATCHED THEN
UPDATE SET a.status = b.status WHERE b.status != 'VALID'
WHEN NOT MATCHED THEN
INSERT (object_id, status) VALUES (b.object_id, b.status)
WHERE b.status != 'VALID';
========================================
-- No matched clause, insert only.
MERGE INTO test1 a USING all_objects b ON (a.object_id = b.object_id)
WHEN NOT MATCHED THEN
INSERT (object_id, status) VALUES (b.object_id, b.status);
==========================================
-- No not-matched clause, update only.
MERGE INTO test1 a USING all_objects b ON (a.object_id = b.object_id)
WHEN MATCHED THEN
UPDATE SET a.status = b.status WHERE b.status != 'VALID';
======================================
-- delete Clause
MERGE INTO test1 a USING all_objects b ON (a.object_id = b.object_id)
WHEN MATCHED THEN
UPDATE SET a.status = b.status WHERE b.status != 'VALID'
DELETE WHERE (b.status = 'VALID');
==========================================