In Tableau Desktop you would reach for a table calculation. In Tableau Next, Ramdosk shows, YoY belongs in the semantic model. This walkthrough explains three modelling decisions first: why Order Item to Order Header is many-to-one, why revenue is calculated at the order item grain so it never double counts, and why every measure needs a clear description. Then it builds current-year, prior-year and growth measures and hands them to Agentforce to find which products and accounts are driving the change.