@JoshRoss: Hey Josh, Will you be able to help me out with update query, Like I make entry in Invoice table and my Project details table get updated. Activity ID is common between Invoice and Project table.
That's just a poor design. I would highly recommend removing the Project table. Since projects are 1 to 1 with invoices, it makes more sense just to get rid of it all together. You could make a Project view based upon the Invoice table, if you needed something named Project.