How do I make a new column from two different tables?

[HamidBee]

How do I create a new table?. The table will be made by subtracting two columns from two different tables?. These are the two tables I am trying to subtract:

 Any help is appreciated. 

[amitchandak]

@HamidBee , You need to have common dimensions like Attributes and can have measure like and analyze against common dimensions

Sum(2020[value]) -sum(2021[value])

[HamidBee]

They should have the same months and values if one was to analyze it row by row. Is that what you mean by common dimensions? Also is there a specific DAX code that is used for subtracting columns like this.

[amitchandak]

@HamidBee , You have a calendar table, In that, you should have a month (without year) to compare against month

You should prefer measure to subtract data across two tables

Bridge Table: https://www.youtube.com/watch?v=Bkf35Roman8&list=PLPaNVDMhUXGaaqV92SBD5X2hk3TMNlHhb&index=19

[HamidBee]

I was thinking to do a measure. But I really would like the difference to be inside a table because I plan to create a colour field. If I can get this calculcation onto a table it would make things alot simpler for me long term. Should I make a measure then put the measure into a table seperated by months. 

[Anonymous]

Hi @HamidBee ,

Can you provide some dummy data?

If it is the following data.

Here's the solution.

1.Create a month column in both tables.

Month = FORMAT([Dates],"MMM")

2.Create a measure.

Difference = 
VAR _20 =
    SUM ( '2020'[Value] )
VAR _21 =
    CALCULATE (
        SUM ( '2021'[Value] ),
        FILTER (
            '2021',
            [Attribute] = MAX ( '2020'[Attribute] )
                && [Month] = MAX ( '2020'[Month] )
        )
    )
RETURN
    _20 - _21

3.Results.

Best Regards,

Stephen Tao

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