I work in a city government, and the fire department would like to have a report that can show how many times during a given period entered by the user that all Ambulances were on a call.
During such periods, the City is technically out of ambulances, and has to request neighboring Cities to cover our areas.
This report needs to show date/times where all Ambulances were on a call, and perhaps some basic info on the call they were on.

I've got a table that lists ambulance ID, dispatch time, completion time, etc. But I've been trying to wrap my head around how to write a report that will find when ALL ambulances are in use during a month. It's easy to just list when ONE is "on a call", but how to zero in on only those spans of time where ALL are in use at the same time?

The results of this report would allow the fire dept to justify adding more ambulances.

Any ideas?

classic macgyver ! do a search on the tech site for articles on this macgyver technique, read them all. its spectacular focus at its coolest.
macgyver makes the period map
you join your db to it.
make a swell ganttchart-looking cross tab. (another classic focus feature...summing up non-numeric fields into a xtab)
What a delightful application.

Thanks Susannah. I've started reading up and it looks like that'll do the trick. It's pretty impressive the kinds of techniques that are buried in WebFOCUS!