How to display a comparison when the key value doesn't exist for 1 of the 2 periods?

[Robert1981]

I have a manufacturing report and I want to do the price and volume variance calculations.

I have in 1 table all details for:
Plant  - Material - Resource - Produced QTY - Consumed QTY - Consumed Cost - EOM date

1234 - D12345678 - Production - 100 -       -           - 8/31/23

1234 - D12345678 - A9874214  -        - 50   - $150  - 8/31/23

1234 - D12345678 - A9874215  -        - 25   - $450  - 8/31/23

1234 - D12345678 - A9874216  -        - 10   -   $12  - 8/31/23

1234 - D12345678 - A9874217  -         - 5   -    $50  - 8/31/23

1234 - D12345678 - Production -   70 -       -            - 7/31/23

1234 - D12345678 - A9874214  -        - 25   - $175  - 7/31/23

1234 - D12345678 - A9874215  -        - 20   - $350  - 7/31/23

1234 - D12345678 - A9874216  -        - 12   -   $16  - 7/31/23

1234 - D12345678 - A9874217  -          - 2   -    $50  - 7/31/23

1234 - D12345677 - Production - 100 -        -           - 7/31/23

1234 - D12345677 - A9874214  -        - 50   -  $150  - 7/31/23

1234 - D12345677 - A9874215  -        - 25   - $450  - 7/31/23

1234 - D12345677 - A9874216  -        - 10   -    $12  - 7/31/23

1234 - D12345677 - A9874217  -         -  5   -    $50  - 7/31/23

The Resource column either indicates's  if the line represents production or consumed Raw material code
In the display visual I set up a time slicer to determine the period I want to compare. If I select August, I would automatically compare with July. I build the formulas to do price and volume variance considering the selected month and the corresponding selected comparison month.

In the above example it works perfectly for material D12345678 since we have data in both periods 7/31 and 8/31. But for D12345677 there is no 8/31 data. It won't create my variance, because there is no D12345677. How do I create the variance regardless. 

My initial thought was to create a union of the master data in the table (Plant, Material, Resource) with the Date table. But that sounds convoluted. 

Is there a better way?

[amitchandak]

@Robert1981 , one of the ways is get the value of any month before

calculate(lastnonblankvalues(Date[Month Year Sort], Sum(Table[Value]) ), Filter(all(Date), Date[Date] < Min(Date[Date]) ))

or when you take diff uses like

divide([This month]-[Last month], [Last Month])

Power BI — Month on Month with or Without Time Intelligence
https://medium.com/@amitchandak.1978/power-bi-mtd-questions-time-intelligence-3-5-64b0b4a4090e
https://www.youtube.com/watch?v=6LUBbvcxtKA