Join on multiple columns using Power query

Anonymous I think you might be trying to apply the logic of some other app you are using to Power BI, and that will not work. You don't actually create JOINS in the Power BI data model. You do in Power Query, but not in DAX. In DAX they are filter relationships, and they either equal or they don't.

However, once you have a filter relationship, you can apply other logic in your formulas (measures) to modify how they work. For example, you might have the following to show cumulative sales through a date on your visual:

Sales Cumulative =
VAR varCurrentDate =
    MAX( Sales[Date] )
RETURN
    CALCULATE(
        [Sales],
        Date[Date] <= varCurrentDate,
        REMOVEFILTERS( Dates[Date] )
    )

That will cause the filter to act in a way that will get all sales prior to today through today.

But that is not a merge operation.

Does that make sense? 

Perhaps tell us what your end goal is, and not ask us to translate Program A logic into Power BI logic. It can cause us to come at this totally wrong, which I've certianly being doing so far. 😁