You should have a common field between to tables. to be able to write any calculated fields. or else i would suggest to do that calculation at Excel level and then bring it in Tableau
The only common fields I would have would be the date ranges. Is there not a way to link a single date in one table that falls within a date range from another?
Upto my knowledge no..
We would generally just create a calc field on the workbook, if we're just going to refresh the same workbook.
Creating something like
IF [Order Date]>=date('2015-01-01') AND [Order Date] <= DATE('2015-05-25') THEN 'Period 1'
ELSEIF [Order Date]>=date('2015-05-26') AND [Order Date] <= DATE('2015-12-03') THEN 'Period 2'
ELSEIF [Order Date]>=date('2015-12-04') AND [Order Date] <= DATE('2016-06-08') THEN 'Period 3'
You could create a second calc field to use as a filter for when period 1 comes around again ... if required.
Hoping this helps.