SQL Server provides server-level roles to help you manage the permissions on a server. These roles are security principals that group other principals. Server-level roles are server-wide in their permissions scope. (Roles are like groups in the Windows operating system.)
Fixed server roles are provided for convenience and backward compatibility. Assign more specific permissions whenever possible.
SQL Server provides nine fixed server roles. The permissions that are granted to the fixed server roles cannot be changed. Beginning with SQL Server 2012, you can create user-defined server roles and add server-level permissions to the user-defined server roles.
You can add server-level principals (SQL Server logins, Windows accounts, and Windows groups) into server-level roles. Each member of a fixed server role can add other logins to that same role. Members of user-defined server roles cannot add other server principals to the role.
The following table shows the fixed server-level roles and their capabilities.
Fixed server-level role
Members of the sysadmin fixed server role can perform any activity in the server.
Members of the serveradmin fixed server role can change server-wide configuration options and shut down the server.
Members of the securityadmin fixed server role manage logins and their properties. They can GRANT, DENY, and REVOKE server-level permissions. They can also GRANT, DENY, and REVOKE database-level permissions if they have access to a database. Additionally, they can reset passwords for SQL Server logins.
Members of the processadmin fixed server role can end processes that are running in an instance of SQL Server.
Members of the setupadmin fixed server role can add and remove linked servers by using Transact-SQL statements. (sysadmin membership is needed when using Management Studio.)
Members of the bulkadmin fixed server role can run the BULK INSERT statement.
The diskadmin fixed server role is used for managing disk files.
Members of the dbcreator fixed server role can create, alter, drop, and restore any database.
Every SQL Server login belongs to the public server role. When a server principal has not been granted or denied specific permissions on a securable object, the user inherits the permissions granted to public on that object. Only assign public permissions on any object when you want the object to be available to all users. You cannot change membership in public.
Each fixed server role has certain permissions assigned to it. For a chart of the permissions assigned to the server roles, see Database Engine Fixed Server and Fixed Database Roles.
The CONTROL SERVER permission is similar but not identical to the sysadmin fixed server role. Permissions do not imply role memberships and role memberships do not grant permissions. (E.g. CONTROL SERVER does not imply membership in the sysadmin fixed server role.) However, it is sometimes possible to impersonate between roles and equivalent permissions. Most DBCC commands and many system procedures require membership in the sysadmin fixed server role. For a list of 171 system stored procedures that require sysadmin membership, see the following blog post by Andreas Wolter CONTROL SERVER vs. sysadmin/sa: permissions, system procedures, DBCC, automatic schema creation and privilege escalation - caveats.
Only server-level permissions can be added to user-defined server roles. To list the server-level permissions, execute the following statement. The server-level permissions are:
The following table explains the commands, views, and functions that you can use to work with server-level roles.
Returns a list of server-level roles.
Returns information about the members of a server-level role.
Displays the permissions of a server-level role.
Indicates whether a SQL Server login is a member of the specified server-level role.
Returns one row for each member of each server-level role.
Adds a login as a member of a server-level role. Deprecated. Use ALTER SERVER ROLE instead.
Removes a SQL Server login or a Windows user or group from a server-level role. Deprecated. Use ALTER SERVER ROLE instead.
Creates a user-defined server role.
Changes the membership of a server role or changes name of a user-defined server role.
Removes a user-defined server role.
Determines membership of server role.