AirpressCollection unique values

I need to return only unique values of a query.
Data is for people with professions. And I need to return a list of only the professions and I dont want them to be repeated. (only unique values)
Right now I use this code and it works, but it repeats the professions associated to more than one person.
I only need the array to return unique values of the field “WEB_tronc_commun”

<?php
$query = new AirpressQuery();
$query->setConfig("SGF");
$query->table("Professions");
$query->view("Utilisation_active");
$query->sort("WEB_tronc_commun");
$events = new AirpressCollection($query);

foreach($events as $e){
    echo '<a href="#' . $e["WEB_tronc_commun"] . '">' . $e["WEB_tronc_commun"] . " | ";
}

?>