<?php
$servername = "localhost";
$username = "root";
$password = "vertrigo";
$dbname = "cw";

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "INSERT INTO ksiazka (nazwisko, imie, telefon, miasto) VALUES ('$zmienna1', '$zmienna2', '$zmienna3', '$zmienna4') ";

if ($conn->query($sql) === TRUE) {
    echo "Wstawiono.";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

$conn->close();
?>
<br>
<a href="druga.php">Listowanie bazy</a>