<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>

<?php

$connection = @mysqli_connect("localhost", "root", "","osmaliga");
if (!$connection)
  {
  die('Nope,nie działa: ' . mysqli_error());
  }

mysqli_select_db($connection,"localhost");
$sql="INSERT INTO zawodnicy (imie,nazwisko,wiek,klub)
VALUES
('$_POST[imie]','$_POST[nazwisko]','$_POST[wiek]','$_POST[klub]')";

if (!mysqli_query($connection,$sql))
  {
  die('Error: ' . mysqli_error($connection));
  }
echo "<p class='bg-primary'>Pomyślnie dodano rekord do klubów</p>";
header( "refresh:3;url=install.php" );
 ?>