i need to get the distinct Ilans. I've tried using removeDuplicates but it didn't remove duplicates from the drop down menu.

function getUniqueCities() {

$cities = DataObject::get('Ilan', '', 'Sehir ASC');
if(!$cities) return false;

$cities->removeDuplicates('Sehir');

return $cities;
}

That would probably be because the query returns entire records, where at least the ID is never duplicated. Maybe only select the city column would work for you?

As here: http://www.silverstripe.org/data-model-questions/show/22128

Are you using 2.4 or 3?? Looks like in SS3 this is only available on an ArrayList not a DataList...

If SS3 you could try
$cities = DataObject::get('Ilan', null, 'Sehir ASC', null, null, 'ArrayList');

It would be best to push all this back into a DB query if possible, with something like GROUP BY Sheir. Other wise it's just loading unnecessary stuff into memory + SQL will be much fast at sorting out the duplicates.