What simple command am I forgetting...I need to hold some duplicates and delete others.

When I use duplicates query, and then try to update another field called "Not Unique", query says "Query is not updateable".

What's the select command I've forgotten?

I am not clear as to your problem. It sounds like you are trying to update the query results instead of updating a field in your table.

Thanks yr comment but as it turned out this was a dumb posting which I self-resolved. It derives from having been deeply involved in data-matching 12,000 names in one source file against 135,000 names in another source file. In doing this all 'Non-Unique' names cannot be considered (Gender, Salutation, Inits & Surname).

I was trying to update with 'Grp By' set which of course won't work, only with a SelectQry.

Having said that I got the desired result of a 31% cross-match which is excellent for the task at hand.
Tks anyway.