Table Index MySQL

mysql>
mysql> CREATE TABLE housewares2
    -> (
    ->  id                      VARCHAR(20),
    ->  description     VARCHAR(255)
    -> );
mysql>
mysql> INSERT INTO housewares2 (id,description)
    ->  VALUES
    ->          ('DIN40672US', 'dining table'),
    ->          ('KIT372UK', 'garbage disposal'),
    ->          ('KIT1729JP', 'microwave oven'),
    ->          ('BED38SG', 'bedside lamp'),
    ->          ('BTH485US', 'shower stall'),
    ->          ('BTH415JP', 'lavatory')
    -> ;
Query OK, 6 rows affected (0.00 sec)
Records: 6  Duplicates: 0  Warnings: 0
mysql>
mysql> SELECT * FROM housewares2;
+------------+------------------+
| id         | description      |
+------------+------------------+
| DIN40672US | dining table     |
| KIT372UK   | garbage disposal |
| KIT1729JP  | microwave oven   |
| BED38SG    | bedside lamp     |
| BTH485US   | shower stall     |
| BTH415JP   | lavatory         |
| DIN40672US | dining table     |
| KIT372UK   | garbage disposal |
| KIT1729JP  | microwave oven   |
| BED38SG    | bedside lamp     |
| BTH485US   | shower stall     |
| BTH415JP   | lavatory         |
+------------+------------------+
12 rows in set (0.00 sec)
mysql>
mysql> SELECT id, LEFT(SUBSTRING(id,4),LENGTH(SUBSTRING(id,4)-2)) FROM housewares2;
+------------+-------------------------------------------------+
| id         | LEFT(SUBSTRING(id,4),LENGTH(SUBSTRING(id,4)-2)) |
+------------+-------------------------------------------------+
| DIN40672US | 40672                                           |
| KIT372UK   | 372                                             |
| KIT1729JP  | 1729                                            |
| BED38SG    | 38                                              |
| BTH485US   | 485                                             |
| BTH415JP   | 415                                             |
| DIN40672US | 40672                                           |
| KIT372UK   | 372                                             |
| KIT1729JP  | 1729                                            |
| BED38SG    | 38                                              |
| BTH485US   | 485                                             |
| BTH415JP   | 415                                             |
+------------+-------------------------------------------------+
12 rows in set (0.00 sec)
mysql>
mysql> drop table housewares2;
Query OK, 0 rows affected (0.00 sec)