Basics

Is there a way to duplicate fields?

Hello,
duplicating fields is not possible. But we have a feature planned to create global list for choice fields. This will allow to use global choice list in choice fields at different places.
Best regards, Alex

How can I change the definition of a field later, after it has been defined? E.g. from text to text (multiline)?

This is not possible. The way around would be to create a new field "Text (multiline)" and transfer the content of the text field to this new field using "Mass data update".

Birger - Ninox Support

How do I delete a number of data records simultaneously. I have tried selecting several records and deleting using the delete button, but only one record is deleted at a time.
See https://screencast.com/t/8u59y2pcp7

Not useful if I have several records to delete.

To delete several records klick on the rows with the right mouse tap and klick on "Delete selected rows"

Brilliant - my half-an-hour of frustration is over!  Thanks.

How do I create a dated notes field for may Database?

How do I create a dated notes field for may Database?

What do you mean by a "dated notes field"? Do you want a date field and a multi-line text field, or a multi-line text field that starts out with a date, or something else? Are you aware that every detail view of every Ninox table includes both a "Comments" tab and a "History" tab?