TRUNCATE TABLE yourTableName;

mysql> create table DeleteAllFromTable
   −> (
   −> PersonId int,
   −> PersonName varchar(200)
   −> );
Query OK, 0 rows affected (0.67 sec)

mysql> insert into DeleteAllFromTable values(100,'Johnson');
Query OK, 1 row affected (0.10 sec)

mysql> insert into DeleteAllFromTable values(101,'John');
Query OK, 1 row affected (0.22 sec)

mysql> insert into DeleteAllFromTable values(102,'Carol');
Query OK, 1 row affected (0.47 sec)

mysql> insert into DeleteAllFromTable values(103,'Sam');
Query OK, 1 row affected (0.19 sec)

mysql> select *from DeleteAllFromTable;

+----------+------------+
| PersonId | PersonName |
+----------+------------+
|      100 | Johnson    |
|      101 | John       |
|      102 | Carol      |
|      103 | Sam        |
+----------+------------+
4 rows in set (0.00 sec)

mysql> TRUNCATE TABLE DeleteAllFromTable;
Query OK, 0 rows affected (0.80 sec)

mysql> select *from DeleteAllFromTable;
Empty set (0.00 sec)