Help Related to Database.

Hello Everyone :P
I need a Help..
I'm working on a project..
I've Databases of
Product
- Product ID, Product Name, Product Type
Location
-Location Id, City, Region, State
Time
-Day, Month , Year
User
User id, username, address, phone number.
and a fact Table : Product ID, Location ID, User ID
I need to create a UI using Java.. I Can do that..
the UI will be having 4 drop downs menus of each table and the application should dynamically generate queries for
Sales By Location
Sales By Product
Sales By month/day/year
Commulative sales by year /month
So Can anyone help me out with Dynamic query generation ?