DROPThe DROP command removes a table from the database. All the tables’ rows, indexes and privileges will also be removed. No DML triggers will be fired. The operation cannot be rolled back.
TRUNCATETRUNCATE removes all rows from a table. The operation cannot be rolled back and no triggers will be fired. As such, TRUCATE is faster and doesn’t use as much undo space as a DELETE.
DELETEThe DELETE command is used to remove rows from a table. A WHERE clause can be used to only remove some rows. If no WHERE condition is specified, all rows will be removed. After performing a DELETE operation you need to COMMIT or ROLLBACK the transaction to make the change permanent or to undo it. Note that this operation will cause all DELETE triggers on the table to fire.
Delete -is a logged operation on a per row basis , this means that the deletion of each row gets logged and physically deleted. You can delete any row that will not violate a constraint,while leaving the foreign key or any other constraint in place.Truncate-is also a logged operation but in different way.Truncate logs the deallocation of the data pages in which the data exists. The deallocation of data pages means that your data rows still actuallyexists in the data pages but the extend have been marked as empty for reuse this is what makes truncate a faster operation over delete. you can not truncate a table that has any foreign key constraint . you will have to remove the constraint , truncate the table and reapply the constraint..