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I am on a SQL Server 2008 where I login with DOMAIN\USER_A

On my database I can see this login is mapped to the user dbo of that database. What I don't understand is that DOMAIN\USER_A is nowhere to be found in the SQL Servers Security Logins.


I can't find DOMAIN\USER_A in the sys.syslogins? What is going on? Can a database user have its own login circumventing the SQL Server?

share|improve this question
Where do you see they are "mapped to" dbo? – Aaron Bertrand Aug 26 '13 at 13:39
May it is an orphaned user: – Shawn Melton Aug 26 '13 at 14:00
up vote 3 down vote accepted

The only way a login has rights to a server is if those rights have been granted. The question is likely: How did these rights get granted?

If DOMAIN\USER_A is a member of some Windows group, then through the rights granted to the group the DOMAIN\USER_A login exists in the server. This is true even if there is no individual entry in sys.database_principals or sys.server_principals for that login.

You can look for the permission paths used by a login as follows:

EXEC xp_logininfo 'DOMAIN\USER_A', 'all'

You might find several permission paths for a login.

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I dont have the rights to execute the that stored procedure :( – Jeppe Aug 26 '13 at 16:15
I will mark your answer as correct since it pointed me in the right direction and figured out the problem. I will have to play around a little on my company network i think to fully understand it. – Jeppe Aug 26 '13 at 16:17
Thank you i understand it now :) gpresult /R shows me my group memberships and i was in a group mapped to a SQL login. – Jeppe Aug 26 '13 at 16:40

Please stop looking at syslogins. This is a deprecated system table that is now a backward compatibility view and is only there for that purpose (to prevent breaking old code).

The user is dbo probably because they created the database.

You should be able to find the login the user is associated with using:

SELECT login_name =, user_name =
  FROM that_database.sys.database_principals AS dp
  INNER JOIN sys.server_principals AS sp
  ON dp.[sid] = sp.[sid];

Now, it may be that the user doesn't have its own login, and has been granted access to the instance via a Windows group.

share|improve this answer
Yields no result as the login do not exist on the SQL Server. – Jeppe Aug 26 '13 at 16:15
@Jeppe probably because, as I said in the next sentence, the login got in via a Windows group. – Aaron Bertrand Aug 26 '13 at 16:23

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