Insert NULL value using prepare()

the quick solution I found is to str_replace empty value.

/* Query */
global $wpdb;
$tablename = $wpdb->prefix . 'data';
$sql = $wpdb->prepare(
    "
    UPDATE $tablename
    SET
        `date` = %s,
    WHERE
        id= %d
    ",
    $_POST['date'],
    $_POST['id']
);
// SQL = UPDATE prefix_data SET `date` = '' WHERE id = 1


$sql = str_replace("''",'NULL', $sql);
// SQL = UPDATE prefix_data SET `date` = NULL WHERE id = 1

$wpdb->query($sql);