The 5 controls use 2 different databases.

The connections are created inside the controls, mainly because the controls
will possibly be used in other programs, so the connection has to remain
with the control; maybe I should be using custom controls but at this time
I'm not sure I need to.

They all use a dataset except one that uses a datareader.

Making the controls invisible is a good idea, I hadn't thought of that.
Currently the controls are visible according to the panel they are in, when
the user clicks on an item, the corresponding panel becomes visible, but I
agree making the controls invisible first would be more practical, then I
can create the connection and dataset when the control becomes visible.

Another question?  How do I pass data from the main page to the control?
The main page has a ClientID; for instance, the user clicks on "address" to
get the address for that particular client.  The address control needs to
query the database and create the dataset according to the clientid, fill in
the fields on the control, then display it on the page.  I tried to create a
class with public properties but would lose the client id when the page
reloads.

Thanks for your help; as you can tell, I'm pretty much a beginner.