使用bind_param PHP在数组中动态执行查询

Question

i actually start using prepare statement and i find interesting but the path is actually not clear to me on how i can insert an array into a bind_param in prepare statement.

from the code below, i use the register_user function to grap all the $register_data which are username, password, email etc and i implode the $register_data in $data and the keys in $field but how do i bind the array in the bind_param so my query can execute correctly and dynamically. Thanks

if (empty($_POST) == false && empty($errors) == true) {

    $register_data = array(
        'email' => $email,
        'username' => $username,
        'first_name' => $first_name,
        'last_name' => $last_name,
        'password' => $password
    );

    register_user($register_data);

    exit();

}


function register_user($register_data) {
    global $connection;

    array_walk($register_data, 'array_sanitize');
    $register_data['password'] = md5($register_data['password']);

    $fields = implode(', ', array_keys($register_data));
    $data = implode(', ', $register_data);

    $stmt = $connection -> prepare("INSERT into users ($fields) VALUES (?)");
    // the problem is around here
    $stmt -> bind_param('s', $data);
    $stmt -> execute();
}