在改进SQL Server7.0系列所实现的安全机制的过程中,Microsoft建立了一种既灵活又强大的安全管理机制,它能够对用户访问SQL Server服务器系统和数据库的安全进行全面地管理。按照本文介绍的步骤,你可以为SQL Server 2000构造出一个灵活...在改进SQL Server7.0系列所实现的安全机制的过程中,Microsoft建立了一种既灵活又强大的安全管理机制,它能够对用户访问SQL Server服务器系统和数据库的安全进行全面地管理。按照本文介绍的步骤,你可以为SQL Server 2000构造出一个灵活的、可管理的安全之门,而且它的安全性经得起考验。展开更多
Constraint is an important aspect of role based access control and is sometimes argued to be the principal motivation for role based access control (RBAC). But so far few authors have discussed consistency maintenan...Constraint is an important aspect of role based access control and is sometimes argued to be the principal motivation for role based access control (RBAC). But so far few authors have discussed consistency maintenance for constraint in RBAC model. Based on researches of constraints among roles and types of inconsistency among constraints, this paper introduces corresponding formal rules, rule based reasoning and corresponding methods to detect, avoid and resolve these inconsistencies. Finally, the paper introduces briefly the application of consistency maintenance in ZD PDM, an enterprise oriented product data management (PDM) system.展开更多
The purpose of the study was to use the Problem-Centered Double-Cycles Instructional Model （PCDC-IM） （1995, Chang） to help the teacher （Lin） implement model-eliciting activity （MEA） in her mathematics classes....The purpose of the study was to use the Problem-Centered Double-Cycles Instructional Model （PCDC-IM） （1995, Chang） to help the teacher （Lin） implement model-eliciting activity （MEA） in her mathematics classes. In this study, there were 31 students divided in 10 groups and engaged in the MEA ＂Who saved the oriental cherry trees＂. Data collections included the learning sheets, journals and debriefing forms of students, teaching and reflection journals, observation reports, and field notes of teachers, reflection journals and interview reports of researchers, video tapes and records of the classes and meetings. There were four parts of the teaching cycle in PCDC-IM, namely task, guidance, environment and analysis. We summarized developing and implementing the MEA in ＂Task＂ aspect, 5 principles and 5 kinds of teachers＇ roles in ＂Guidance＂ aspect, 2 elements and 5 features in ＂Environment＂ aspect and data in ＂Analysis＂ aspect. The findings showed that PCDC-IM was helpful for mathematics teachers who want to change their instruction from lecture into modeling teaching.展开更多
文摘针对某煤矿机械制造企业数据库系统用户数量较多而影响数据库系统安全性能的问题,提出了一种基于SQL Server的数据库系统安全机制的设计方案;详细介绍了该安全机制中登录身份模式选择、应用程序验证、创建SQL Server组、设置数据库访问、设置与分配用户权限以及其他安全机制的设计;指出在设计该安全机制时,应首先创建全局组,通过SQL Server Users组获得服务器访问,通过具体数据库组获得数据库访问权限,然后根据用户访问需求创建数据库角色并对角色分配权限,最后全局组通过加入角色获得权限,从而可确保数据库系统的安全。实际应用验证了该安全机制的可行性和有效性。
文摘在改进SQL Server7.0系列所实现的安全机制的过程中,Microsoft建立了一种既灵活又强大的安全管理机制,它能够对用户访问SQL Server服务器系统和数据库的安全进行全面地管理。按照本文介绍的步骤,你可以为SQL Server 2000构造出一个灵活的、可管理的安全之门,而且它的安全性经得起考验。
文摘Constraint is an important aspect of role based access control and is sometimes argued to be the principal motivation for role based access control (RBAC). But so far few authors have discussed consistency maintenance for constraint in RBAC model. Based on researches of constraints among roles and types of inconsistency among constraints, this paper introduces corresponding formal rules, rule based reasoning and corresponding methods to detect, avoid and resolve these inconsistencies. Finally, the paper introduces briefly the application of consistency maintenance in ZD PDM, an enterprise oriented product data management (PDM) system.
文摘The purpose of the study was to use the Problem-Centered Double-Cycles Instructional Model （PCDC-IM） （1995, Chang） to help the teacher （Lin） implement model-eliciting activity （MEA） in her mathematics classes. In this study, there were 31 students divided in 10 groups and engaged in the MEA ＂Who saved the oriental cherry trees＂. Data collections included the learning sheets, journals and debriefing forms of students, teaching and reflection journals, observation reports, and field notes of teachers, reflection journals and interview reports of researchers, video tapes and records of the classes and meetings. There were four parts of the teaching cycle in PCDC-IM, namely task, guidance, environment and analysis. We summarized developing and implementing the MEA in ＂Task＂ aspect, 5 principles and 5 kinds of teachers＇ roles in ＂Guidance＂ aspect, 2 elements and 5 features in ＂Environment＂ aspect and data in ＂Analysis＂ aspect. The findings showed that PCDC-IM was helpful for mathematics teachers who want to change their instruction from lecture into modeling teaching.
