I have ud 4 db acces 2000

Is there a way to do solf my prob

I lett users update an empty cel in my database (this is no prob )

No i want that the users of my site only can update a cel that is empty so that the users cant overwrite cels another user has filt in

For example you have a table : table 1
With 2 fields 1 unique ID and one remarks
i let them do a querry on unique id an leth them update the cel of remark but i want that they only can update a cel of field remark if its empty

Greets DarKPsyChO