Is date considered last month true or false

[rbreneman]

Hi!

I have a date table where I've created a column with the DAX line below to give me a true/false value if the date is last month. I'm taking the month number of today's date and subtracting 1, and using if(and to match against the month number and year of dates in my table. This is working great as currently all sepetember 2020 dates show True, everything else shows False. My problem will be come January the DAX will calculate "0" as the month number. What can I add to this DAX to account for this and get it to return "12" instead of "0". I'm sure there is a fairly simple way to do this, I'm just not seeing it and need a fresh set of eyes! Thanks!

Last Month? = IF(AND(MONTH(TODAY()) -1 = DateTable[Month Num],YEAR(TODAY()) = DateTable[Year]),TRUE(),FALSE())

[dedelman_clng · Accepted solution]

Hi @rbreneman 

Try this

Last Month? = 
var __ThisMonth = MONTH(TODAY())
var __ThisYear = YEAR(TODAY())
var __LastMonth = IF(__ThisMonth = 1, 12, __ThisMonth - 1)
var __LastMonthYear = IF(__ThisMonth = 1, __ThisYear - 1, __ThisYear)
return
IF (
    AND (
        DateTable[Month Num] = __LastMonth,
        DateTable[Year] = __LastMonthYear
    ),
    TRUE (),
    FALSE ()
)

Hope this helps

David

[rbreneman]

Thanks so much! That works perfectly. Huge help! I appreciate you laying it out like that too, I tend to write in one line but it certainly helps to understand it when it's broken out on multiple lines.