<?php

$servername = "localhost";
$username = "root";
$password = "314314";
$DB = "myDB";

$conn = new mysqli($servername, $username, $password);
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error ."\n</br>");
}

$sql="USE myDB";
if ($conn->query($sql) === TRUE) {
    echo "database selected successfully"."\n</br>";
} else {
    echo "Error selecting database: " . $conn->error ."\n</br>";
}

$sql = "UPDATE customer
SET lastname = 'UNKNOWN'
WHERE lastname IS NULL OR lastname='';";

if ($conn->query($sql) === TRUE) {
    echo "Table customer updated successfully"."\n</br>";
} else {
    echo "Error creating table: " . $conn->error ."\n</br>";
}

$sql = "SELECT id, lastname
FROM customer;";

if ($conn->query($sql) === TRUE) {
    echo "Selected successfully"."\n</br>";
} else {
    echo "Error selecting: " . $conn->error ."\n</br>";
}

while ($row = $conn->query($sql))
{
    ?>

    <tr>
    <td><?php echo $row['id']; ?></td>
    <td><?php echo $row['lastname']; ?></td>
    </tr>

    <?php
}

$conn->close();