box select thành phố - quận huyện [php + mysql]

<script type="text/javascript">
var states = new Array();

states['1'] = new Array('Quận 1','Quận 2','Quận 3');
states['2'] = new Array('Quận 4','Quận 5','Quận 6');

function setStates() {
  cntrySel = document.getElementById('country');
  stateList = states[cntrySel.value];
  changeSelect('state', stateList, stateList);
  setCities();
}


function changeSelect(fieldID, newOptions, newValues) {
  selectField = document.getElementById(fieldID);
  selectField.options.length = 0;
  for (i=0; i<newOptions.length; i++) {
    selectField.options[selectField.length] = new Option(newOptions[i], newValues[i]);
  }
}


function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

addLoadEvent(function() {
  setStates();
});
</script>

					<select name="country" id="country" onchange="setStates();">
<?php
$query_thongtin=mysql_query('select * from thongtin') or die (mysql_error());
while($row_thongtin=mysql_fetch_array($query_thongtin))
{
echo '<option value="'.$row_thongtin['id'].'">'.$row_thongtin['thanhpho'].'</option>';
}
?>
					</select>

					<select name="state" id="state">
						<option value="1">Quận 1</option>
						<option value="2">Quận 2</option>
						<option value="3">Quận 3</option>
					</select>