[Resolved] datatable AJAX render property is duplicating rows

{ 
                        "data": null,
 
                render: function(data, type, row) { 
                var disc = row.ispercent == 0 ? row.discount : row.discount+'%';            
                return disc; 
                }
                     },

 $("#classid").change(function(){
       var sessionid = $("#sessionid").val();
       var classid = $(this).val();
       $.ajax({
               url : "<?php echo site_url('Ajax/getStuDiscByClassID'); ?>",
               method : "POST",
               mydata : {sessionid: sessionid, classid: classid},
               async : true,
               dataType : 'json',
               success: function(mydata)
               {
$('#example').DataTable({
           destroy: true,
           data : data,
           columns: [
                   { data: "id"},
                   {data: "studentname"},
                    { data: 'fathername'},
                    {
                       "data": null,

               render: function(data, type, row) {
               var disc = row.ispercent == 0 ? row.discount : row.discount+'%';
               return disc;
               }
                    },
               ],
               dom: 'Blfrtip',
               buttons: [
               'copyHtml5',
               'excelHtml5',
               'csvHtml5',
               'pdfHtml5',
               ],

               search: true
        });
        }
        });
           return false;
   });