Basic inventory calculations

Let us start by answering the most basic question: what is the actual inventory? Because of the way we have modeled our data, this one is easy to do:

Actual Inventory =
CALCULATE(
    SUM(fInventory[Quantity]),
    fInventory[Type] = 0
)

All we need to do is retrieve the rows with [Type] = 0, as it is in those where the actual inventory is stored.

There is one issue with this calculation, however: it assumes that we have selected the whole of the Calendar table, or at least made a selection that includes the date with the Type 0 rows. After all, when we select last year, the rows containing the current inventory will not be selected. It would be better to create a measure that returns a result for any selection on Calendar.

If we assume that we have some selection in Calendar, the first question to ask is: which exact date do we pick to return the status for? After all, the inventory status is strictly date-specific.

The common practice...