I have noticed that when I open SQL server enterprise manager and I navigate to the list of users under a specific DB, I found users with"Name" but some have no "Login Name" value. What does this means? Does it means that the
1)users cannot log into the server at all?
2)its a system ID(or application ID so no user will be able to use it to log on and only applications can use it to access the database?)
3)there is a single sign on so once the user sign into the server, they can access the db without authentication again?
My second question pertains to the users under the "Security" group in enterprise manager.When lets say "a" is here and "a" is also present in the db users, it means that "a" can access and change data in the db right? But if "b" is in the security group but not in the db users, it means that it cannot log onto the db but only make changes to the server only?
My third question: If default database is master, it means that that user can make changes to all the database?
A huge thanks to anyone who answers my questions!