Hello MMJ,

If you are trying to both retrieve and submit data, then you would have to
create an InfoPath form which has the SQL connection as the main Data
connection. To do this please follow the steps below
1. In Design a Form task pane, click on New from Data connection
2. Create a data connection to the specific SQL DB in the data connection
wizard that comes up. In the last window of the data connection wizard you
will be told if Submit is allowed or not to this specific table in the
database.
3. This will create some default UI to be able to insert.
4. Submit is allowed based on text shown in the last window in the wizard -
you will be able to enable submission of forms using Tools -> Submitting
forms. This will allow you to update existing data in the database.

Hope this helps!