php - Pros and cons of connecting more than one database in single script -

Assume that the user has two databases hosted on one host and I need to join them so that I Any time you can add a connection code without using a table.

I implemented it in CodeIgniter to add the authentication details of both the databases in the database.php file and load the required database with the $-> Load-> Database ('dbname'); In the script

Now, for the basic PHP, we can do this:

  mysql_connect ('host', 'user', 'password', 'Port', 'dbname'); // Connection with a database  

This was connected to my first database.

Now, I want to connect to another database:

1) I have not closed up the connection and with the other

  mysql_connect (' Host ',' user ',' password ',' port ',' dbname1 ');  

2) Would it be bad practice to do this? Will it consume more items? Do we have to first stop anyway?