Thanks for you answer. The reason for my question was that when I read the assignment, I only read "A period always refers to a real calendar month ..." and skipped this part "... with period 1 being the month of the planned start date". I will make a s

So if the planned_start is 2012-04-06 and the planned_finish is 2012-05-25 then there can be no effort in period 3 - and if there is, we can just skip this? And another question. Can Activities be in more than 1 year? If so how should a case with an ac

How about efforts before the planned_start ?

The solution is made by generating a row for each combination of days in the Activity and rows in the Efforts-table. The amount is calculated by dividing with the number of days a given activity has in a certain period. The amounts are added up as