Insert, Update, Delete in Oracle

Inserting Data

INSERT INTO customers (name, email, city) VALUES
  ('Priya Sharma', 'priya@example.com', 'Mumbai');

INSERT INTO customers (name, email, city) VALUES
  ('Rahul Patel', 'rahul@example.com', NULL);

COMMIT;

Why COMMIT Matters

Oracle is transactional. Changes are invisible to other sessions until you run COMMIT, and you can undo them with ROLLBACK before that.

Updating

UPDATE customers SET city = 'Pune' WHERE id = 1;
COMMIT;

Deleting Rows

DELETE FROM customers WHERE id = 3;
COMMIT;

Insert-Or-Update With MERGE

MERGE INTO customers c
USING (SELECT 1 AS id, 'Priya' AS name, 'priya@example.com' AS email FROM dual) s
ON (c.email = s.email)
WHEN MATCHED THEN UPDATE SET c.name = s.name
WHEN NOT MATCHED THEN INSERT (name, email) VALUES (s.name, s.email);

Key Points

• INSERT, UPDATE and DELETE change data.
• COMMIT makes changes permanent; ROLLBACK undoes them.
• MERGE performs insert-or-update in one statement.
• dual is a one-row dummy table used for expressions.