Paul, thanks for the reply, delayed response but to answer your two questions:

1. Both batch and row-by-row queries feature hard-coded numeric values, which are presumably keys for the table concerned. It is much more common to use a dynamic selection query, or to use keys from a table (usually a temporary one). Do the queries concerned really look like this?

Yes! The queries actually do look like this, basically someone else will hand me an excel spreadsheet of IDs they've reviewed and want the changes made fo - I'll just concatenate these IDs in Excel and run the update.

2. Neither query checks that the condition that caused them to be selected for change, still applies. Your example is a change from 'Mr' to 'Mrs' - in that context, the update queries ought to check that the source record still contains 'Mr', otherwise you risk a lost update (where someone else has changed the data in the meantime, their change is lost).

This is true and the actual queries would do that check, for similicity I omitted that here.

The defensive approach you mention is very interesting and introduces a few ideas I'd either not heard of or not thought of, I don't think we're at the stage that these would be necessary at the moment but it's something I'd like to play with before they do become a necessity, thanks for the information there 🙂