如何处理PHP结果？

Question

actually I am retrieving some data mysql from using a PHP query

<?php
    $id=$_POST['id'];

 $result="SELECT button,row_id,char1,char2,char3,char4,char5,char6,match_time FROM selected_characters  WHERE oauth_uid= '".$id."'";
$data = mysqli_query($conn,$result);
while($rows = mysqli_fetch_array($data)){
    $JSONDataArray[]=array('button'=>$rows['button'],'rows'=>$rows['row_id'],'time'=>$rows['match_time'],'p1'=>$rows['char1'],'p2'=>$rows['char2'],'p3'=>$rows['char3'],'p4'=>$rows['char4'],'p5'=>$rows['char5'],'p6'=>$rows['char6']);

}

echo json_encode($JSONDataArray);
?>

Here you can clearly see if oauth_uid = $id then data will retrieve otherwise when case is true data is retrieved successfully but when case is not true it give an error

Notice: Undefined variable: JSONDataArray in C:\xampp\htdocs\gaming\phpetrieverb.php on line 24
null

Here is my AJAX

                $.ajax({
                url: 'php/retrieverb.php',
                type: 'post',
                data: {id:uuid},
                success: function(response) {

                       var objs = JSON.parse(response);
                       if(objs!='') {      

                    $.each(objs, function(i, item) {
                //        var images = document.querySelector('tbody').querySelectorAll('img');
                        var n = Math.floor(Math.random() *999999);
                        var distance = (new Date(objs[i].time)).getTime() - (new Date(current)).getTime();
                        document.getElementById(objs[i].button).remove();
                        var parent=document.getElementById(objs[i].rows);
                        var timer = document.createElement("h");
                        timer.setAttribute("id","timer"+n);
                        parent.appendChild(timer);
                        var x = setInterval(function() {
                        var days = Math.floor(distance / (1000 * 60 * 60 * 24));
                        var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
                        var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
                        var seconds = Math.floor((distance % (1000 * 60)) / 1000);

                        document.getElementById("timer"+n).innerHTML ="Tiempo restante: "+ days + "days " + hours + "hours " + minutes + "mins " + seconds + "secs ";
                            distance -= 1000;
                     if (distance < 0) {
                    clearInterval(x);
                    document.getElementById("timer"+n).innerHTML = "¡El tiempo de partida ha comenzado!";

                }
            }, 1000);
                          })

                }
                    else if(objs==''){
                        alert("ERROR");
                    }
                }
                });