HTTP ERROR 500 mysql php? -

i try insert data http error 500 dont know why.i saw problem starts when prepare query.i try insert mutiple rows txt file.

$conn = new mysqli("localhost", "***", "****", "***"); // check connection if ($conn->connect_error) { die("connection failed: " . $conn->connect_error); }      $contents = file_get_contents("cars.txt");     $pollfields = explode(',', $contents);      $query = "insert table (`name`) values (?)";      $zz = $mysqli->prepare($query);      $zz ->bind_param("s", $bb);      $mysqli->query("start transaction");     foreach ($pollfields $bb) {         $zz->execute();     }     $zz->close();     $mysqli->query("commit"); 

i need defined it

$conn = new mysqli("localhost", "***", "****", "***"); // check connection if ($conn->connect_error) { die("connection failed: " . $conn->connect_error); }      $contents = file_get_contents("cars.txt");     $pollfields = explode(',', $contents);      $query = "insert table (`name`) values (?)";      $zz = $conn->prepare($query);      $zz ->bind_param("s", $bb);      $conn->query("start transaction");     foreach ($pollfields $bb) {         $zz->execute();     }     $zz->close();     $mysqli->query("commit");