用MySQL结果刷新div

I'm using this ajax simple code for refresh a div with mySql result. Work, but it's a correct way? For few connections it's ok but for a lot of connections....?

setInterval(function(){ 
 $.ajax({
      type: "GET",
      url: "current_number.php",
      dataType: 'html',
      success: function(data) {           
          $("#current_number").html(""+data+"");
        }
    });
 }, 500);   

thanks