controls not visible inside formview control

I am trying to write a query to select data from one table based on the result
of a drop down list that pulls data from another table. The query I am writing is:

"SELECT church.churchName, church.churchId AS Expr1
FROM [churches]
WHERE ([deanery.deaneryId] = @churches.deaneryId)"
I am using a sql source control

Now I found an example from a website that pulls data from one drop down list and uses
the selected value to populate the second drop down list. But, the controls are not part of a formview
control. So my question is how do I get the dropdownlist control that is located inside of a formview
control to show up in the drop down list in the select where clause window. Specifically

1) I select - specify columns from table or view radio button
2) next I click where button
3) In the drop down titled column I choose - deaneryI ...