Using MSSQL

Assign a database security role to a Windows security group

EXEC sp_grantlogin 'BUILTIN\Administrators'
EXEC sp_addsrvrolemember 'BUILTIN\Administrators','sysadmin'

List the members of a database server group

EXEC master..xp_logininfo
  @acctname = 'Builtin\Administrators',
  @option = 'members'     -- show group members