I\'m using the following T-SQL to obtain role members from my SQL Server 2008 R2 database:
select rp.name as database_role, mp.name as database_user from sys.dat
Here is another way
SELECT dp.name , us.name FROM sys.sysusers us right JOIN sys.database_role_members rm ON us.uid = rm.member_principal_id JOIN sys.database_principals dp ON rm.role_principal_id = dp.principal_id