一张表中根据一个字段分组，查询分组中另一个字段最大值
表：
| id | score | uid |
|---|---|---|
| 1 | 100 | 1 |
| 2 | 100 | 1 |
| 3 | 90 | 1 |
| 4 | 80 | 2 |
| 5 | 100 | 2 |
| 6 | 50 | 3 |
| 7 | 90 | 3 |
| 8 | 80 | 3 |
sql
select t.* from user_test_result t where score = (select max(score) from user_test_result where open_id = t.open_id) group by t.open_id;结果：
| id | score | uid |
|---|---|---|
| 1 | 100 | 1 |
| 5 | 100 | 2 |
| 7 | 90 | 3 |