在jquery和ajax中使用PHP插入数据时

here below code using insertdata in jquery and ajax is not working please slow this code

<script type="text/javascript">
    $(document).ready(function(){
        $("#btn").click(function()
        {
            var fname=$("#fname").val();
            var lname=$("#lname").val();
            //alert(fname);
            var URL="insertprocess.php";
            var datastring='fname'+fname+'&lname'+lname;

            $.ajax()
            
        });
    });

</script>

</div>

Problem is here use = equal

var datastring='fname='+fname+'&lname='+lname;

If still getting any issue share complete code