[nox-dev] How to use VLOG_DBG to print out the message?

[LEO]

Good morning,


I am trying to link to mysql database in routing.cc（in the get_route function）. 
I would like to print something on the screen to make sure that I successfully 
link to the database. I tried to use the VLOG_DBG(lg, "…………") but nothing 
appeared on the screen.


I am wondering how to use this VLOG_DBG to print out some message on the screen?


My code is as following
************************************************************************************************************************
Routing_module::get_route(const RouteId& id, RoutePtr& route) const
{


MYSQL_RES* res;
MYSQL mysql;
mysql_init(&mysql);


if(!mysql_real_connect(&mysql,"localhost","root","123456","rule",0,NULL,0))
{
      VLOG_DBG(lg, "Not able to link to the database");
}


VLOG_DBG(lg, "Successfully link to the database");
……
}
*************************************************************************************************************************