Add field to field in all records

End of the year: for every record, I need to add the amount in one field to the amount in another field of the same record.
Sales this year + Sales all years = Sales all years.
How can I do that in a batch process?
Thanks for your input.

Manually: Menu > Fields > Morph …
Procedurally: with a formulafill statement.

worked! Thanks KLM

sorry, KJM. not the Dutch airline!!!