How to modify key in php array

$data =array(
             'classname' =>' 我们不一样',
             'id' =>    ' 6666',
          );
          //更改 id key值为cate_id
 
        $datas =array(
           'classname' =>$data['classname'],
            'cate_id'  =>$data['id'],
        );
       $arr3 =array_combine(array_keys($datas),$data);
        echo &#39;<pre class="brush:php;toolbar:false">&#39;;
        var_dump($arr3);
        echo &#39;

array(2) {
  ["classname"]=>
  string(16) " 我们不一样"
  ["cate_id"]=>
  string(5) " 6666"
}

$data =array(
            'classname' =>' 我们不一样',
            'id' =>    ' 6666',
        );
        //更改 id key值为cate_id
         foreach ($data as $v=>$k){
             $data['cate_id'] =$data['id'];   //key字段赋值
         }
          unset($data['id']);    //销毁原字段id key
          dump($data);die;