if (isset($_POST["delete"])) {
    $predmet = htmlspecialchars($_POST["predmety"]);
    $id = 0;

    $sql8 = "SELECT id_predmet FROM predmet WHERE nazov = '$predmet'";
    $result = $conn->query($sql8);

    if ($result->num_rows > 0) {
        while ($row = $result->fetch_assoc()) {
            $id = $row["id_predmet"];
        }
    } else {
        echo "0 results";
    }
    echo "$id";
    $sql9 = "DELETE FROM zaznam WHERE id_predmet ='$id'";
    $sql10 = "DELETE FROM predmet WHERE id_predmet='$id'";
    $sql11 = "DELETE FROM vysledky WHERE id_predmet='$id'";

    if (mysqli_query($conn, $sql9)) {
        if (mysqli_query($conn, $sql10)) {
            if (mysqli_query($conn, $sql11)) {
            echo "delete success";
        } else {
                echo "Error updating record: " . mysqli_error($conn);
            }
        } else {
            echo "Error updating record: " . mysqli_error($conn);
        }
    } else {
        echo "Error updating record: " . mysqli_error($conn);
    }
    header("Refresh:0");
}