I've got a conference database, with 4 tables:

Contacts

Events

ContactEventsJoin

Activities

There is a many-many relationship between Contacts and Events with ID fields through ContactEventsJoin and there is a one to many relationship between Events and activities (Many activities at 1 event).

Each activity has a cost so in the Activities Table, there's a Name Field and a cost Field for each record (and an Event ID field providing the relationship to Events).

In the ContactsEventsJoin Table, there is a field for activities. I've made it a checkbox set using a list of the related values in the Activities table so that I can check off what activities some one is attending at each event.

How can I get it to add up all of the costs for the activities that are checked off in that field?

Thanks in advance.

Do you have a second TO of the Activities table connected to ContactEventsJoin? If not, add one (ContactEventsJoin::yourcheckbox = Activities 2::ActivityID).

Then in ContactEventsJoin define a calculation field =

Sum ( Activities 2::Cost )