I am trying to fetch the list of id's associated with mobile number using following code.

$sql = "SELECT id FROM complaints WHERE mobile=1555521555";

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

$res = mysqli_fetch_array($r);

$result = array();

array_push($result,array(
     "id"=>$res['id']
 )
);

header('Content-Type:application/json');
echo json_encode(array("result"=>$result));

mysqli_close($conn);

But it only result me a single id every time as below instead of list of id's

{"result":[{"id":"82925318"}]}

Actual query result is -

How do I get the multiple results in array of arrays format or in multidimensional array? Like below -

{"result":[{"id":"82925318"}, {"id":"82925319"}]}