Export (0) Print
Expand All
2 out of 3 rated this helpful - Rate this topic

Principals (Database Engine)

Principals are entities that can request SQL Server resources. Like other components of the SQL Server authorization model, principals can be arranged in a hierarchy. The scope of influence of a principal depends on the scope of the definition of the principal: Windows, server, database; and whether the principal is indivisible or a collection. A Windows Login is an example of an indivisible principal, and a Windows Group is an example of a principal that is a collection. Every principal has a security identifier (SID).

Windows-level principals

  • Windows Domain Login

  • Windows Local Login

SQL Server-level principal

  • SQL Server Login

Database-level principals

  • Database User

  • Database Role

  • Application Role

The SQL Server sa log in is a server-level principal. By default, it is created when an instance is installed. In SQL Server 2005 and SQL Server 2008, the default database of sa is master. This is a change of behavior from earlier versions of SQL Server.

Every database user belongs to the public database role. When a user has not been granted or denied specific permissions on a securable, the user inherits the permissions granted to public on that securable.

INFORMATION_SCHEMA and sys

Every database includes two entities that appear as users in catalog views: INFORMATION_SCHEMA and sys. These entities are required by SQL Server. They are not principals, and they cannot be modified or dropped.

Server principals with names enclosed by double hash marks (##) are for internal system use only. The following principals are created from certificates when SQL Server is installed, and should not be deleted.

  • ##MS_SQLResourceSigningCertificate##

  • ##MS_SQLReplicationSigningCertificate##

  • ##MS_SQLAuthenticatorCertificate##

  • ##MS_AgentSigningCertificate##

  • ##MS_PolicyEventProcessingLogin##

  • ##MS_PolicySigningCertificate##

  • ##MS_PolicyTsqlExecutionLogin##

By definition, a client and a database server are security principals and can be secured. These entities can be mutually authenticated before a secure network connection is established. SQL Server supports the Kerberos authentication protocol, which defines how clients interact with a network authentication service.

For more information about the SQL Server implementation of Kerberos support, see Kerberos Authentication and SQL Server.

Did you find this helpful?
(1500 characters remaining)
Thank you for your feedback

Community Additions

ADD
Show:
© 2014 Microsoft. All rights reserved.