Get user ID after logging in

wp_login hook provides access to two parameters: $user->user_login (string) and $user ( WP_User ). To pass them into your function you will need to add a priority (default is 10) and request 2 arguments from the add_action() call:

function login_cookie($user_login, $user) {
    global $wpdb;

    var_dump($user); // get WP_User object

    //Get current user ID
    $id = $user->ID;
    .....
}

add_action( 'wp_login', 'login_cookie', 10, 2 );