php - Display categories from a database -

i updating my site. can see have list of catagories (example: free offers, gifts, accessories).

these catagories list promotions , link single page , each 1 of promotion saved in mysql under dbname xclocouk_mobile , table mobi , each 1 has promo_cat field name category underneath it.

i know how connect database. want know how index page read , display list of catagories found under promo_cat listed above?

i need them list title shown on page done manually. not want display duplicates.

how can accomplish this?

 $q = "select promo_cat mobi";  $result = mysql_query($q,$connection);  while($output = mysql_fetch_array($result)) {     echo $output['category'];  } 

edit:

this list duplicates if there duplicates in database, else won't.

if have duplicates in db, use "select distinct(promo_cat) .. "