What is the difference between DELETE, TRUNCATE, and DROP?

Great question! DELETE, TRUNCATE, and DROP are all SQL commands used to remove data or structures from a database, but they differ significantly in scope, performance, and rollback capability. Here's a breakdown:

🔸 1. DELETE

• Use: Removes specific rows from a table using a WHERE clause.
• Can be rolled back: ✅ Yes (if used within a transaction).
• Triggers: ✅ Yes (fires ON DELETE triggers).
• Table structure remains: ✅ Yes.
• Auto-increment counter reset: ❌ No.
• Speed: 🔻 Slower for large datasets (logs each row deletion).

Example:

DELETE FROM employees WHERE department = 'HR';

🔸 2. TRUNCATE

• Use: Removes all rows from a table (no WHERE clause).
• Can be rolled back: ⚠️ Depends on DBMS (e.g., No in MySQL without transaction).
• Triggers: ❌ No (doesn't fire ON DELETE triggers).
• Table structure remains: ✅ Yes.
• Auto-increment counter reset: ✅ Yes (in most DBMS like MySQL, SQL Server).
• Speed: ⚡ Much faster than DELETE (minimal logging).

Example:

TRUNCATE TABLE employees;

🔸 3. DROP

• Use: Completely removes the table and its structure.
• Can be rolled back: ❌ No (once dropped, it's gone unless restored from backup).
• Triggers: ❌ Not applicable.
• Table structure remains: ❌ No.
• Auto-increment counter reset: ✅ Yes (table is removed).
• Speed: ⚡ Very fast (removes entire object).

Example:

DROP TABLE employees;

🧠 Summary Table:

Let me know if you’d like a visual comparison or want to see this demonstrated in a SQL environment!