DAX Time Intelligence with Conditional Logic - excel

Question

I have a "sales" table with team ID, payment type and date (see example below):
I want to write a DAX formula that will "lookup" the prior month's sales amount for a "Monthly" team and the 3 month prior sales amount for a "Quarterly" team. The lookup also needs to be filtered by team ID, so the prior sales belong to the same team.
Here's an example of the desired output (Change in Sales) :
PriorMonthSales =CALCULATE(
SUM(Table[Sales]),
FILTER(
Table[TeamID]&&
Table[Date] - 1
)
PriorQuarterSales =CALCULATE(
SUM(Table[Sales]),
FILTER(
Table[TeamID]&&
Table[Date] - 3
)
PriorSales = IF(Table[PaymentType] = "Monthly",PriorMonthSales, PriorQuarterSales)
These formulas obviously don't produce the desired result, but I am sharing them here to show my approach to solving this. Perhaps, someone more knowledgeable here can assist with the correct syntax and logic.
Thanks!

Answer 1

To calculate the total of the previous month/quarter you can add a calculated column. However you need to change your month column to a date.
jan 16 => 1/1/2016
formula:
=
IF (
myTable[paymenttype] = "monthly",
CALCULATE (
SUM ( myTable[sales] ),
FILTER (
myTable,
myTable[TeamID] = EARLIER ( myTable[TeamID] )
&& DATEADD ( myTable[date], 1, MONTH ) = EARLIER ( myTable[date] )
&& myTable[paymenttype] = EARLIER ( myTable[paymenttype] )
)
),
CALCULATE (
SUM ( myTable[sales] ),
FILTER (
myTable,
myTable[TeamID] = EARLIER ( myTable[TeamID] )
&& DATEADD ( myTable[date], 3, MONTH ) = EARLIER ( myTable[date] )
&& myTable[paymenttype] = EARLIER ( myTable[paymenttype] )
)
)
)