+-----------+-------+--------+------+----------------+
| id        | grade | weight | snum | time           |
+-----------+-------+--------+------+----------------+
| 213456758 | 2     |     10 |    1 | 20030423150119 |
| 213456758 | 5     |     10 |    2 | 20030423150119 |
| 213456758 | 4     |      5 |    3 | 20030423150119 |
| 555555555 | 2     |      5 |    4 | 20030423150214 |
+-----------+-------+--------+------+----------------+