<form id="contact-form" method="post" action="cms_data.php" role="form">
    <div class="col-sm-12">
        <h2>id</h2>
        <input name="id" type="text" placeholder="<?php echo $id;?>" value="1">
    </div>
    <div class="col-sm-12">
        <h2>Omschrijving</h2>
        <textarea name="omschrijving" type="text" style="height:220px;width:100%;resize:none;"><?php echo $omschrijving;?></textarea>
    </div>
    <div class="col-sm-12">
        <h2>Datum</h2>
        <input name="datum" type="text" value="<?php echo $datum;?>">
    </div>
    <div class="col-sm-12">
        <h2>Tijd</h2>
        <input name="tijd" type="text" value="<?php echo $tijd;?>">
    </div>
    <div class="col-sm-12">
        <h2>Locatie</h2>
        <input name="locatie" type="text" value="<?php echo $locatie;?>">
    </div>
    <div class="col-sm-12">
        <h2>Dresscode</h2>
        <input name="dresscode" type="text" value="<?php echo $dresscode;?>">
    </div>
    <div class="col-sm-12 text-right">
        <input type="submit" class="btn btn-success btn-send" value="Versturen" id="sent" <?php // echo $_SESSION['disabled']; ?>>
        <a href="update-cms.php">Update </a>
    </div>
</form>

<?php session_start();?>
<?php
    $servername = "localhost";
    $username = "xxx";
    $password = "xxx";
    $dbname = "xxx";

    // Create connection
    $conn = mysqli_connect($servername, $username, $password, $dbname);
    //echo '<div style="width:100%;background:green;color:#FFF;font-size:2rem;text-align:center;">Connected to '. $dbname. '</div>';

    // Check connection
    if (!$conn) {
        die("Connection failed: " . mysqli_connect_error());
    }

$id = $_POST['id'];
$omschrijving = $_POST["omschrijving"];
$datum = $_POST["datum"];
$item = $_POST["tijd"];
$locatie = $_POST["locatie"];
$dresscode = $_POST["dresscode"];

$quote = iconv("UTF-8", "WINDOWS-1252//TRANSLIT");
$date = date('Y-m-d');
date_default_timezone_set("Europe/Amsterdam");
$time = date("h:i:sa");
$sql = "INSERT INTO $table (ID, Omschrijving, Datum, Tijd, Locatie, Dresscode )
                        VALUES ('" .$id."','" .$omschrijving."','".$datum."',' ".$item."','".$locatie."','".$dresscode."')";

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

$conn->close();
?>

<?php session_start();?>
<?php
    $servername = "localhost";
    $username = "xxx";
    $password = "xxx";
    $dbname = "xxx";

    // Create connection
    $conn = mysqli_connect($servername, $username, $password, $dbname);
    //echo '<div style="width:100%;background:green;color:#FFF;font-size:2rem;text-align:center;">Connected to '. $dbname. '</div>';

    // Check connection
    if (!$conn) {
        die("Connection failed: " . mysqli_connect_error());
    }

$id = $_POST['id'];
$omschrijving = $_POST["omschrijving"];
$datum = $_POST["datum"];
$item = $_POST["tijd"];
$locatie = $_POST["locatie"];
$dresscode = $_POST["dresscode"];

$quote = iconv("UTF-8", "WINDOWS-1252//TRANSLIT");
$date = date('Y-m-d');
date_default_timezone_set("Europe/Amsterdam");
$time = date("h:i:sa");
$sql = "UPDATE $table SET
    Omschrijving = '$omschrijving', Datum = '$datum', Tijd = '$item', Locatie = '$locatie', Dresscode = '$dresscode' WHERE ID = '1'";

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

$conn->close();
?>