Database Principals

Principals are entities that can request resources. Principal can either be an individual 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.

sys.database_principals gives a list of all the principals

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

IMG Source: http://www.codeproject.com/KB/database/sql-server-logins.aspx

Source:http://msdn.microsoft.com/en-us/library/ms181127.aspx