TRUNCATE TABLE hr.emp;
Truncate a table deletes all rows in a table and releases used space.
Corresponding indexes are trunate.
The effects of using this command are as follows:
1、ALL rows in the table are deleted.
2、NO undo data is generated and the command commits implicitly because TRUNCATE TABLE is a DDL
command.
3、Correspondig indexes are also truncate.
4、A table that is being referenced by a foreign key cannot be truncated.
5、The delete triggers do not fire when this command is used.