It's a simple matter to connect to any database via ODBC or JDBC drivers. Below shows a connection and the tables and fields in the database.
Next, you create a subset of the database, called a View. This makes the data easier to handle and is also used to manage user permissions to access the data.
Create as many Views as you like so it's easier to manage your data.
The Data Sources tab allows you to add a database or web service, connect to it and select a subset of that data for use.
Databases:
When you connect to your database, you will be shown a list of tables and fields in that database. Next you create a view of the data (a subset of the tables and fields you want to extract data from).
Web services
After entering the webservices WSDL url, a list of operations is shown. Select an operator to extract data from.