Dear David:
Once you have this working as a query, changing it to update an
existing column is a simple derivative of that query.
Now, the column you want to replace: is it a primary key, or a unique
index to the table? If there are such constraints on the column, you
will probably have to remove them temporarily before you can update
the column. In addition, if there are any relationships to other
tables involving this column, then the situation is much more complex.
To get my help, please continue with the questions I asked before.
Tom Ellison
Microsoft Access MVP
Ellison Enterprises - Your One Stop IT Experts