I have created a portal which shows details of ads booked for specific clients. ie the portal is based on a client relationship.

I want to be able further filter the portal to only show records for each client between particular dates.

Welcome millmaine!

A simple way to do date relationships is to use Month and Year as the filters. This can be a stored calculation in the related file:

ClientID_Month_Year (calculation, text result) = ClientID & " " & MonthName(AdDate) & " " & Year(AdDate)

Then use globals for the selection fields in the Client file, and build a calculated parent key:

gMonth (global, text)

gYear (global, number)

ClientID_Month_Year (calculation, text result) = ClientID & " " & gMonth & " " & gYear

If you want a true date range relationship, they are pretty complex. You have to build large multikeys on both sides of the relationship. You should look into Mikhail Edoshin's Smart Ranges technique for a good method (there's sample files in the 1st Edition page):

http://www.onegasoft.com/tools/smartranges/

This is another case where version 7 shines: you could have a combined equijoin (clientID in client = clientID in ad) and double-non-equijoin relationship for the two dates (>= and <=).