$sql = 'SELECT * from customer';
  $statement = $connection->prepare($sql);
  $statement->execute();
  if($statement->rowCount())
  {
    $row_all = $statement->fetchall(PDO::FETCH_ASSOC);
  
    echo json_encode($row_all);         
  }  
  elseif(!$statement->rowCount())
  {
    echo "no rows";
  }