Comparing columns in two different tables

[aditidhooria]

I have a table named Sales Transaction in which I have two fields : Revenue Amount and Cost Amount. I need to calculate Gross Margin (GM) which is the difference of Revenue Amount and Cost Amount using DAX expression. 

Can someone help please ?

[MattAllington · Accepted solution]

Firstly, make sure you write a measure and not a column. Read about that here http://exceleratorbi.com.au/calculated-columns-vs-measures-dax/

A measure something like this should do it. 

GM = sumx(Sales,Sales[Revenue] -Sales[Cost])

[aditidhooria]

Thanks Matt for the quick response. I am trying the same.