Datetable as Filter

Hi,

I have a fact table with date and revenue. Now I want to see ony the revenue of the actual month. I created a measure, something like

SUMX(revenue, FILTER(facttable, facttable[date}>blabla)

Now someone told me it would be better to have a date table and use this for filtering.

Now my question: Do I need to create a calculated "filtered" data table and create a relationship or is there another way with a measure?

Thx Chris