multiple database connectivity

[eluser]ranjitbd[/eluser]
$DB1 = $this->load->database('holidaydb', TRUE);
//where i have to add this line (within model class constructor)


//and what i will write in the config/database.php file after the following line
$db['default']['database'] = "tmartdb";
$DB1['database'] = "holidaydb"; //is it correct or
$DB1['default']['database'] = "holidaydb";//this one is correct //$DB1 is it case sensitive

//how i will get the data from that database

$this->$DB1->query(); //is it correct?
$DB1->query(); //is it correct?