php

                    <?php
                    if(isset($_GET['input']))
                    {
                    $con=mysqli_connect("localhost","root","admin321","php");

                    if (mysqli_connect_errno())
                      {
                      echo "Failed to connect to MySQL: " . mysqli_connect_error();
                      }
                       $name=$_GET['input'];
                     $sql="SELECT * FROM tab where value LIKE '%".$name."%'";
                    $r = mysqli_query($con,$sql);
                            $data = array();
                            while($row = mysqli_fetch_assoc($r)) {
                             $data[] = $row;
                             }
                             function buildtree($src_arr, $parent_id = 0, $tree = array())
                    {
                        foreach($src_arr as $idx => $row)
                        {
                            if($row['parent'] == $parent_id)
                            {
                                foreach($row as $k => $v)
                                    $tree[$row['id']][$k] = $v;
                                unset($src_arr[$idx]);
                                $tree[$row['id']]['children'] = buildtree($src_arr, $row['id']);
                            }
                        }
                        ksort($tree);
                        return $tree;
                    }

                    function insertIntoNestedArray(&$array, $searchItem){

                        if($searchItem['parent'] == 0){
                            array_push($array, $searchItem);
                            return;
                        }
                        if(empty($array)){ return; }
                     array_walk($array, function(&$item, $key, $searchItem){
                        if($item['id'] == $searchItem['parent']){
                                array_push($item['children'], $searchItem);
                                return;
                            }
                            insertIntoNestedArray($item['children'], $searchItem);
                    }, $searchItem);
                    }
                    $nestedArray = array();
                    foreach($data as $itemData){

                        $nestedArrayItem['id'] = $itemData['id'];
                        $nestedArrayItem['name'] = $itemData['name'];
                     $nestedArrayItem['parent'] = $itemData['parent'];
                        $nestedArrayItem['children'] = array();

                        insertIntoNestedArray($nestedArray, $nestedArrayItem);
                    }
                    header('Content-Type: application/json');
                    header('Content-Type: text/html; charset=utf-8');
                         $json= json_encode($nestedArray);
                    echo $json = substr($json, 1, -1);

                    }
                    ?>

json output
              {
   "id":"4",
   "name":"B",
   "parent":"0",
   "children":[
      {
         "id":"5",
         "name":"B1",
         "parent":"4",
         "children":[

         ]
      }
   ]
}