Index.php
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "uuu";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "INSERT INTO dane (ident, uwagi, serwis)
VALUES ('$_POST[ident]','$_POST[uwagi]','$_POST[serwis]')";

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

$conn->close();

header('location:index.php');

?>


Dane.php
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "uuu";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "SELECT id, ident, uwagi, serwis FROM dane";
$result = $conn->query($sql);
echo '<form action="delete.php" method="POST">';
echo '<table><tr><th>LP</th><th>ID</th><th>Uwagi</th><th>Serwis</th></tr>';
if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        echo "<tr><td>{$row['id']}</td><td>{$row['ident']}</td><td>{$row['uwagi']}</td><td>{$row['serwis']}</td><td><td><input type='checkbox' value ='" . $row['id'] . "' name='kasuj[]'></td></tr>";
}
echo '</table>';
echo "<input type='submit' name='delete' value='delete'>";
}

else {
    echo "0 results";
}

$conn->close();
?>
<?php


delete.php
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "uuu";

$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}


if(isset($_POST['delete'])){

   foreach ($_POST["kasuj"] as $id){
   $sql = "DELETE FROM dane WHERE id='$id'";
    mysqli_query($conn,"$sql * FROM dane");
}
   echo "Wpis skasowany";
}

$conn->close();

header('location:dane.php');

?>