Updating from Excel (1 Viewer)

I have a database that contains information for our internal plant hire costing.
The data has been appended from several excel worksheets.
Each week there are changes to some of the information and I need a solution to update the table without duplicating a record.
I don't have a key for the database.
I have defined the name in the excel worksheets.
Will I duplicate records with differing information if I append the same worksheets or will it overwrite the original data with the updated data as I require.

Thanks in advance for any help.

Hi. If you "append," it will add the new data and potentially create duplicates. To change existing records, you'll have to use an "update" query.

I've written a lengthy article discussing different methods of synchronising data with external tables.
See http://www.mendipdatasystems.co.uk/synchronise-data-1/4594514001

Each method has advantages and disadvantages and some may be more relevant to you than others.
As you have no primary key fields you need to be very careful to avoid duplication particularly if you have null values in any fields