How can I get data from the previous record?

[dylan]

I have a database which calculates times for a motor race. The unique fields are passing time and car no. I calculate everything from these.

Some calculations (eg time between two cars) I do by subtracting a value in the current record (eg passing time) from its value in the previous record.

What's the best way to do this? Can I use the "AutoEnter from Last Record" feature? I'm importing 100 records at a time, so I'm not creating new records here.

What I've done for now is to write a script that works through all the records and cuts and pastes values from one record to the next. This works well and gives correct results. However, I would like to speed it up. For a 2 hour race, my calculations take 2 minutes - not much good if I want to publish updated times on the web every 30s.

Any suggestions would be very much appreciated.

[LiveOak]

If you ALWAYS want to find the time between two records in entry order, this will work:

Define Fields:

Record# = Status(CurrentRecordID)

Last Record# = Record# - 1

Time

Define Relationship with same file (call relationship "LastCar"):

Last Record# matches Record#

Define Field:

Elapsed Time = Time - LastCar::Time

Again, as long as you want the elapsed time to be between records in creation order, this will work. If you want to differentiate by Car# or something, you must build a more complex relationship. -bd