Formula Help: How to get sum of previous month value?

[akim55]

helpIf the  table looks like this:

03/01/2022	8
03/03/2022	3
03/04/2022	3
03/15/2022	5
03/21/2022	7
04/01/2022	6
04/15/2022	1
04/18/2022	9

What would be the formula to get the sum of the previous month from the current month date? 

Right now, I have the previous month's sum formula as:

IF ToNumber(DateTimeMonth(DateTimeToday()))-tonumber(DateTimeMonth([spent_date])) = 1 AND DateTimeYear([spent_date]) = DateTimeYear(DateTimeToday())THEN [Sum_hours] ELSE 0 ENDIF

If the formula is correct, can someone explain why it is correct and/or if there is a better way to get the data? Thank you in advance. 

[gabrielvilella]

The expression is correct. I encourage you to take a look at the documentation and see what each of those formulas means.

https://help.alteryx.com/20214/designer/datetime-functions 

Also, here is another way of doing this, which I personally think it is simpler and easier to understand:

IF DateTimeTrim([spent_date],'month') = DateTimeAdd(DateTimeTrim(DateTimeNow(),'month'),-1,'month')
THEN [Sum_hours]
ELSE 0
ENDIF

[PhilipMannering]

@gabrielvilella And you can also replace 

DateTimeTrim(DateTimeNow(),'month')

with

DateTimeFirstOfMonth()