A role-based access control model is used to make a system secure. A role concept shows a job function in an enterprise. Traditional locking protocols and timestamp ordering schedulers are based on principles “first-comer-winner” and “timestamp order” to make multiple conflicting transactions serializable, respectively. In this paper, we discuss a concurrency control based on the significancy of roles assigned to transactions. We define a significantly dominant relation on roles. We discuss a role ordering (RO) scheduler based on the role concept. We evaluate the RO scheduler compared with the two-phase locking (2PL) protocol.