SQL Server/T-SQL Tutorial/System Functions/sp AddSrvRoleMember
A statement that assigns a user to a server role
EXEC sp_AddSrvRoleMember JohnDoe, sysadmin
How to assign a user to a server role
The syntax for sp_AddSrvRoleMember
sp_AddSrvRoleMember [@loginame = ] "login_ID",
[@rolename = ] "server_role_name"