In the Connection::connect(SQLString &url, Properties &props) method, it seems that a property in the url will override a property in props, which I think is non-standard. In the following code will attempt to connect with the username "unknown" instead of "myuser"

   sql::Properties p;

   sql::Driver* driver = sql::mariadb::get_driver_instance();

   sql::Connection *conn;

   p["user"] = "myuser";

   conn = driver->connect("tcp://host?user=unknown", p);