Calculation based on Date Range
I know there are a lot of threads out there relating to Date Range Calculations but I couldn't quite find the one to help me.
I have a portal where each row is a new record that has a Date field and Number field on it. The calculation I need is just to subtract the Number field between two dates that will be selected. What is the best way to acheive this? I am aware that I will need 2 global fields, start date and end date but I am not sure how to link those global fields to the Date field in the portal so when selected will choose the Number values corresponding to those dates. How would I then write the calculation?
Any help would be appreciated.