Server roles debuted in SQL Server 7.0. You use these helpful security tools to assign a predefined set of permissions to one or more database logins. The sysadmin role is the most powerful fixed server role because its members can perform any function on the server. You can use the remaining limited-function fixed server roles, listed below, to grant limited permissions to specific types of users and revoke or reassign permissions as users' job duties change. Remember, a change in a role's permissions applies to all members of the role, and changes to a user's permissions don't take effect until the next time the user logs in.