mysql group by

<pre name="code" class="sql">mysql> select * from t2;
+------+----------+------+
| name | address  | flag |
+------+----------+------+
| a    | aaaaaaaa | 1    |
| a    | bbbbbb   | 1    |
| b    | bbbbbb   | 1    |
| b    | bbbbbb   | 2    |
| b    | bbbbbb   | 2    |
| a    | wwwwwww  | 2    |
| c    | wwwwwww  | 2    |
+------+----------+------+
7 rows in set (0.00 sec)

mysql> select name,address from t2 group by name;
+------+----------+
| name | address  |
+------+----------+
| a    | aaaaaaaa |
| b    | bbbbbb   |
| c    | wwwwwww  |
+------+----------+
3 rows in set (0.00 sec)

mysql> select * from t2 group by name;
+------+----------+------+
| name | address  | flag |
+------+----------+------+
| a    | aaaaaaaa | 1    |
| b    | bbbbbb   | 1    |
| c    | wwwwwww  | 2    |
+------+----------+------+
3 rows in set (0.00 sec)