mysql> select * from test;
+----+----------+-------+-----------+
| id | name     | score | subject   |
+----+----------+-------+-----------+
|  1 | xiaoming |    89 | shuxue    |
|  2 | xiaohong |    89 | shuxue    |
|  3 | xiaohong |    80 | english   |
|  4 | xiaohong |    80 | physics   |
|  5 | xiaohong |    80 | astronaut |
|  6 | xiaoming |    80 | physics   |
|  7 | xiaoming |    80 | astronaut |
|  8 | xiaoming |    80 | english   |
|  9 | xiaobai  |    80 | astronaut |
| 10 | xiaobai  |    80 | english   |
| 11 | xiaobai  |    80 | physics   |
| 12 | xiaobai  |    80 | shuxue    |
| 13 | xiaohei  |    80 | astronaut |
| 14 | xiaohei  |    80 | shuxue    |
| 15 | xiaohei  |    80 | physics   |
| 16 | xiaohei  |    80 | english   |
+----+----------+-------+-----------+
16 rows in set (0.00 sec)


mysql> select distinct(name) from test;
+----------+
| name     |
+----------+
| xiaoming |
| xiaohong |
| xiaobai  |
| xiaohei  |
+----------+
4 rows in set (0.00 sec)