Originally Posted by
June7
Having this value generated by dependent calculation is risky. What if one of the detail records is deleted? This sequence will then have a gap.
This sequential numbering of order detail records can be generated when need. Textboxes on report have a RunningSum property that can give this output. It can also be done in a query.
If you really want to do this during data entry, will require some VBA coding. Try presetting the textbox DefaultValue property to 1. That way the first record will always start with 1. Then in the AfterUpdate event of the textbox, reset the DefaultValue property = Num + 1.