Hi RobChin-2066,
Users can only read data in the database and cannot modify the data or database objects when the database sate is set to Read-only.
From your description, I did a test in my environment. We can’t add a user to the db_datareader role for read-only database, because the database is read-only, we failed to update it.
You can try to follow the steps to achieve this goal.
- Change the database to read and write state(set the database Read-only option to false from SSMS)
- Add the user to the db_datareader role for this database
- Change the database to Read-only state(set the database Read-only option to true from SSMS)
Then the user ( not in admin membership) can access the database.
If the response helped, do "Accept Answer" and upvote it.
Best regards,
Cathy