function show_photo(photoid){
      var url="show_ajax.asp?photoid=" + photoid ;
      if (window.XMLHttpRequest) { 
           http_request = new XMLHttpRequest();
       } else if (window.ActiveXObject) { 
           http_request = new ActiveXObject("Microsoft.XMLHTTP");
       }
       http_request.onreadystatechange = alertContents;
       http_request.open('GET', url, true);
       http_request.send(null);
   } 

    
    function alertContents() {

       if (http_request.readyState == 4) {
           if (http_request.status == 200) {
               document.getElementById('photo').innerHTML = http_request.responseText;
           } else {
               document.getElementById('photo').innerHTML = "(Error retrieving photo)";
           }
       }

   }