Affiliates by @itthinx : get_affiliate_id

public static function get_affiliate_id ( ) {
    global $wpdb;

    $pname = get_option( 'aff_pname', AFFILIATES_PNAME );

    $affiliate_id = "";
    $user_id = get_current_user_id();
    if ( $user_id && affiliates_user_is_affiliate( $user_id ) ) {
        $affiliates_table = _affiliates_get_tablename( 'affiliates' );
        $affiliates_users_table = _affiliates_get_tablename( 'affiliates_users' );
        if ( $affiliate_id = $wpdb->get_var( $wpdb->prepare(
            "SELECT $affiliates_users_table.affiliate_id FROM $affiliates_users_table LEFT JOIN $affiliates_table ON $affiliates_users_table.affiliate_id = $affiliates_table.affiliate_id WHERE $affiliates_users_table.user_id = %d AND $affiliates_table.status = 'active'",
            intval( $user_id )
        ))) {
            $affiliate_id = affiliates_encode_affiliate_id( $affiliate_id );
        }
    }
    return $affiliate_id;
}