What is Difference between truncate delete and drop

DELETE
DELETE command is used to remove rows from table, it can be used with WHERE clause After DELETE operation you need to COMMIT or ROLLBACK to make the changes permanent DELETE command will cause all DELETE triggers on the table to fire DELETE is DML command
TRUNCATE
TRUNCATE removes all rows from tabl,it do not accept WHERE clause The operation cannot be ROLLBACKED and no trigger will be fired TRUNCATE is faster and it does not use much undo space as compared to DELETE TRUNCATE is DDL command
DROP
DROP command removes a table from the database. All the table's rows, indexes and privileges will also be removed No DML triggers will be fired. The operation cannot be rolled back DROP is DDL command

      DELETE FROM employee WHERE job = 'CLERK';

      TRUNCATE TABLE employee;

      DROP TABLE employee;