DROP, DELETE, and TRUNCATE

Here’s a comparison of DROP, DELETE, and TRUNCATE in SQL:

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Aspect	DROP	DELETE	TRUNCATE
Purpose	Removes an entire table or database.	Removes specific rows from a table.	Removes all rows from a table.
DML/DDL	DDL (Data Definition Language).	DML (Data Manipulation Language).	DDL (Data Definition Language).
Deletes Data Only?	Deletes both structure and data.	Deletes data, keeps table structure.	Deletes data, keeps table structure.
WHERE Clause	Not applicable.	Can use WHERE to filter rows.	Cannot use WHERE.
Performance	Faster for dropping structure.	Slower for large data (logged).	Faster (minimal logging).
Rollback Support	Cannot be rolled back.	Can be rolled back if in a transaction.	Cannot be rolled back.
Resets Identity?	Yes, as table is removed.	No, retains identity sequence.	Yes, resets identity sequence.

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Examples:

1. DROP:

   DROP TABLE employees;
   

2. DELETE:

   DELETE FROM employees WHERE department_id = 101;
   

3. TRUNCATE:

   TRUNCATE TABLE employees;