How can I set variable php and mysql code

I want to set a variable “name”,
I tried: if(isset($_POST[‘name’])), But not result.

I was also looking for other options but could not get results.

I have a PHP code:

  <?php
  $servername = "localhost";
  $username = "..";
  $password = "..";
  $dbname = "..";

  $conn = new mysqli($servername, $username, $password, $dbname);
  $response = array();
  $posts = array();

  $sql = "SELECT name, addres, status, date  FROM silknet WHERE name='test'";

  $result=mysqli_query($conn,$sql);


  while($row=mysqli_fetch_array($result)) { 
     $name=$row['name']; 
     $addres=$row['addres']; 
     $status=$row['status'];
     $date=$row['date'];

  $response[] = array('name'=> $name, 'addres'=> $addres, 'status'=>$status, 
  'date'=>$date);
  } 

  echo json_encode($response);
  ?>