How to query list of members updated/registered for a given date range

I have a database table as below.

Id 1 and 4 are old members and their data is updated (as seen in updated date column).

Id 2 and 3 new members.

So now how we can query in SQL Server and get list of members updated/registered for a given date range?

Answer

coalesce() would be a good fit here. If [updated date] is NULL, it will then look at [registration date]

select * 
from yourtable
where coalesce([updated date],[registration date]) between '2021-01-01' and '2021-01-05'