DB connection to a table outside Joomla DB

I wish to connect my form to a table in a database different from my Joomla database.
When I click on the DB connection tab I only get a list of tables that belong to my Joomla DB ie all have a jos_ prefix.
How do I connect to a table that belongs to a different DB please?

Hi Trv,

That's correct, the DB Connection list only shows the tables from the Joomla database.

You can hand-code a connection to any other database that is accessible from your site. The code to create the connection is in the Joomla docs Wiki

Bob

Many thanks.