We need the first 5 digits of Postal Ref in dimLocation Dimension Table.

To do that, we need to make a new Calculated Field:

Name: Post Code

Formula: LEFT([Postal Ref],5)

We also want a calculated field for max of Sales

Name: Max Sales

Formula: Max([Sales])

In the finest level of granularity, where there is no aggregation, Max([Sales]) and SUM([Sales]) are idenntical. However, when there is some aggregation in the context, they are different. SUM([Sales]) is the default aggregation by Tableau.

Each OrderID and ProductName represents the finest level of granularity (no aggregation). However, OrderID itself has aggregation and measures are responsive to the context unless, there is only one product in the order.