mysql_select_db - błąd

<?php
echo "TEST MYSQL<br><br>";
$servername = "localhost";
$username = "redspot";
$password = "4U8q3R2t";
$db_name = "spizarnia";

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

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 
echo "Connected successfully<br><br>";



echo "SELECT TEST:<br>";
$sql = "SELECT id, name, surname FROM al_user";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. " " . $row["surname"]. "<br>";
    }
} else {
    echo "0 results<br><br>";
}


echo "<br>";
echo "DBSELECT TEST:<br>";
$db_selected = mysql_select_db('spizarnia', $conn);
if (!$db_selected) {
    die ('Can\'t use spizarnia : ' . mysql_error());
}
else
{
	 die ('Database changed');
}
?>