select 
	r.name role_name,
	u.name db_login,
	u.type_desc
from (select name,principal_id
		from sys.database_principals where type = 'R') r
	join sys.database_role_members rm 
		on (r.principal_id = rm.role_principal_id)
	join (select name,type_desc,principal_id
		from sys.database_principals where type != 'R') u 
		on (rm.member_principal_id = u.principal_id )