SUM rows up to specific column

Hi everyone,

I have a table with a list of project financials split across periods. The period column is a text column based on financial periods. I need two measures which calculate based off a selected period from a slicer:

1. A measure which sums all periods from the selected period onwards
2. A measure which identifies the next period from the selected period, and sums all periods from that point onwards

The closest equivalent I can think of is SUMPRODUCT in Excel, (e.g. =SUMPRODUCT(([periodrow]>=DATE([SELECTED DATE]))*[VALUES])).

However even in Excel I am not sure if this is possible unless I change the data type to a date. I can also transform the data structure and unpivot it if that helps.

Any ideas?

AmiK