if ($_SERVER['REQUEST_METHOD'] == 'POST' && isset($_POST['formid']) && $_POST['formid'] == 'form1')
    {
        $mysql_server = 'my cloud sql instance ip';
        $mysql_database = 'DB1';
        $mysql_table = 'Table1';
        $mysql_username = 'User1';
        $mysql_password = 'PW1';

$db = mysqli_connect($mysql_server, $mysql_username, $mysql_password) or die('Failed to connect to database server!<br>'.mysqli_error($db));

env_variables:
      # Replace USER, PASSWORD, DATABASE, and CONNECTION_NAME with the
      # values obtained when configuring your Cloud SQL instance.
      MYSQL_DSN: mysql:unix_socket=/cloudsql/INSTANCE_CONNECTION_NAME;dbname=DB1
      MYSQL_USER: User1
      MYSQL_PASSWORD: PW1