Creating a dynamic querry ??

Hi there, I am building a picture search engine with a gui where the user can choose categories and then choose from those categories several points. It is almost impossible to build a querry out of that. I am having a problem keeping it dynamic. It works if I am naming the category, but I would like to make it dynamic Here is an example what I am trying to get: assuming there are following values: $glacier = array("g_one", "g_two"); $lake = array ("l_one", "l_two"); $mountain = array ("m_one", "m_two"); // this returns the value for glacier echo $glacier[1]; // g_two // This code is creating a querry. User has a gui where he can choose between the categories. // It should loop through all possibilities Thats why I tryed to make the $glacier $$category But somehow this does not work // The problem is, that I want to loop through all. So I do not know if it is a glacier, lake or mountain the user selected building the querry: if ($glacier[0] == 'empty'){ // show all glaciers $search = "glacier IS NOT NULL"; } else{ // show particular $search = "glacier ="; for($i=0; $i<count($glacier); $i++){ $search .= $glacier[$i]; # add OR if it is not the last in the array if ($i < (count($glacier)-1)) $search .= " OR glacier ="; } } Do you see my trouble?? Thanx for any help Cheers Andy