mysql> EXPLAIN latest_cn_no;
+-----------+-----------------+------+-----+---------+----------------+
| Field     | Type            | Null | Key | Default | Extra          |
+-----------+-----------------+------+-----+---------+----------------+
| rec_id    | int(4) unsigned |      | PRI | NULL    | auto_increment |
| branchID  | int(4) unsigned |      |     | 0       |                |
| for_year  | varchar(4)      |      |     |         |                |
| cur_cn_no | int(5) unsigned |      |     | 0       |                |
+-----------+-----------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)