Mysql optimization skills necessary -EXPLAIN

 

mysql> EXPLAIN select * from `order` a where a.order_no;
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
| id | select_type | table | partitions | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra       |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
|  1 | SIMPLE      | a     | NULL       | ALL  | NULL          | NULL | NULL    | NULL | 1917 |       90 | Using where |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
1 row in set