如果在PHP中存在重复项时，如何只显示一次MySQL数据库记录？

Suppose my db looks like this:

id | person_id | hobby       | time
-----------------------------------
1  | 67        | golf        | mon
2  | 33        | reading     | tues
3  | 67        | baseball    | fri
4  | 67        | golf        | sun

I want to display a list of all the hobbies of person with id 67 on a page.

If I do this:

$query = mysql_query("SELECT * FROM hobbies WHERE person_id = '67'");

while ($row = mysql_fetch_assoc($query)) {

   echo $row['hobby'];

}

I wil get:

golf
baseball
golf

I want duplicate hobbies entered by the same person id to show only once, so it will show:

golf
baseball

And by duplicate I mean however many redundant times the same hobby by the same person is entered in a database (as long as it's more than once it should shown only once).

How can this be done?

$query = mysql_query("SELECT DISTINCT `hobby` FROM `hobbies` WHERE `person_id` = '67'");

DISTINCT will not show duplicates for hobby.

Documentation.

$query = mysql_query("SELECT * FROM hobbies WHERE person_id = '67' GROUP BY hobby");

while ($row = mysql_fetch_assoc($query)) {
   echo $row['hobby'];
}