Oracle DML Basics 📝

Mentor's Note: Creating the table was building the room. DML is the act of moving furniture in, rearranging it, or throwing it away. But remember: in Oracle, changes aren't permanent until you say so! 💡

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🌟 The Scenario: The Office Move 📦

• INSERT: Bringing a new desk into the room.
• UPDATE: Changing the label on a folder.
• DELETE: Removing an old chair that broke.

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💻 1. INSERT (Add Data)

-- Standard Insert
INSERT INTO employees (id, name, salary)
VALUES (101, 'Rahul', 50000);

-- Bulk Insert from another table
INSERT INTO graduates_archive
SELECT * FROM students WHERE status = 'Finished';

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💻 2. UPDATE (Modify Data) ✏️

Warning: Always use a WHERE clause!

UPDATE employees
SET salary = salary * 1.10 -- 10% raise
WHERE department_id = 20;

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💻 3. DELETE (Remove Data) ❌

Warning: This is permanent!

DELETE FROM employees
WHERE id = 105;

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🏗️ Architect's Note: Transactions & Redo Logs 🛡️

Oracle is a Transactional database.

• The Architect's Secret: When you run DML, Oracle doesn't change the data on the disk immediately. It writes to the Redo Log first.
• The Safety Net: Use COMMIT to save permanently or ROLLBACK to undo your mistakes!
• Architecture Tip: Keep your transactions short. Long transactions hold "Locks" on the rows, which can slow down other users.

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📈 Learning Path

• ← Back: Sequences
• Next: INSERT ALL (Multi-table) →