Preserving an audit trail

If you need to preserve an audit trail of all versions of a record, structure you system to prevent record editors from 'Save'ing the record, but only give them the 'Save as new record' button*. This forces each record update to actually create a new record, leaving the previous version untouched. Your queries will need to be adapted to only show the most recent version of each 'record', except for those designed to show the edit history.

*The button can be displayed as 'Save' so as not to confuse editors with the subtelty of the mechanism.