mysql distinct()函数 去重

mysql> select * from table1;
+----------+------------+-----+---------------------+
| name_new | transactor | pid | order_date          |
+----------+------------+-----+---------------------+
| 1hahha   | 1xiaohong  |    | -- :: |
| 2hahha   | 2xiaohong  |    | -- :: |
| 3hahha   | 3xiaohong  |    | -- :: |
| 4hahha   | 4xiaohong  |    | -- :: |
| 3hahha   | bob        |    | -- :: |
| 3hahha   | lee        |    | -- :: |
| 3hahha   | lee        |    | -- :: |
| 3hahha   | lee        |    | -- :: |
| 3hahha   | bob        |    | -- :: |
| 3hahha   | bob        |   | -- :: |
+----------+------------+-----+---------------------+
 rows in set (0.00 sec)

mysql> select distinct transactor from table1;
+------------+
| transactor |
+------------+
| 1xiaohong  |
| 2xiaohong  |
| 3xiaohong  |
| 4xiaohong  |
| bob        |
| lee        |
+------------+
 rows in set (0.00 sec)

mysql> select distinct(transactor) from table1;
+------------+
| transactor |
+------------+
| 1xiaohong  |
| 2xiaohong  |
| 3xiaohong  |
| 4xiaohong  |
| bob        |
| lee        |
+------------+
 rows in set (0.00 sec)