How to use KEEPFILTERS in DAX iterator functions to preserve arbitrarily shaped filters in context transition.
Article and download: https://sql.bi/705054?aff=yt
How to learn DAX: https://www.sqlbi.com/guides/dax/?aff=yt
The definitive guide to DAX: https://www.sqlbi.com/books/the-definitive-guide-to-dax-2nd-edition/?aff=yt