SQL Server数据库是当今信息管理系统中有代表性的大型网络数据库之一。文中讨论在SQL Server 2008中通过触发器技术实现数据完整性的机制,介绍触发器的概念、分类,重点论述DML触发器的实现过程,结合具体实例,设计DML触发器监督财务人...SQL Server数据库是当今信息管理系统中有代表性的大型网络数据库之一。文中讨论在SQL Server 2008中通过触发器技术实现数据完整性的机制,介绍触发器的概念、分类,重点论述DML触发器的实现过程,结合具体实例,设计DML触发器监督财务人员对资金的各种业务操作,包括插入、删除和更新记录,分析了触发器设计的基本步骤,并改进触发器设计,使审计表能够记录全部变化的数据,从而反映了触发器的应用在提高系统性能、维护数据库完整性、有效性等方面的强大功能。展开更多
Most of the previous studies concerning checking the integrity constraints in distributed database derive simplified forms of the initial integrity constraints with the sufficiency property, since the sufficient test ...Most of the previous studies concerning checking the integrity constraints in distributed database derive simplified forms of the initial integrity constraints with the sufficiency property, since the sufficient test is known to be cheaper than the complete test and its initial integrity constraint as it involves less data to be transferred across the network and can always be evaluated at the target site （single site）. Their studies are limited as they depend strictly on the assumption that an update operation will be executed at a site where the relation specified in the update operation is located, which is not always true. Hence, the sufficient test, which is proven to be local test by previous study, is no longer appropriate. This paper proposes an approach to checking integrity constraints in a distributed database by utilizing as much as possible the local information stored at the target site. The proposed approach derives support tests as an alternative to the existing complete and sufficient tests proposed by previous researchers with the intention to increase the number of local checking regardless the location of the submitted update operation. Several analyses have been performed to evaluate the proposed approach, and the results show that support tests can benefit the distributed database, where local constraint checking can be achieved.展开更多
触发器是一种特殊的存储过程,它的主要功能是监视用户对数据表的修改,文章以SQL Server 2005数据库系统为例,介绍了触发器的类型、作用,探讨了触发器在维护数据表之间一致性、保持数据完整性的强大功能,重点讨论触发器在数据库开发中的...触发器是一种特殊的存储过程,它的主要功能是监视用户对数据表的修改,文章以SQL Server 2005数据库系统为例,介绍了触发器的类型、作用,探讨了触发器在维护数据表之间一致性、保持数据完整性的强大功能,重点讨论触发器在数据库开发中的实际应用。展开更多
文摘SQL Server数据库是当今信息管理系统中有代表性的大型网络数据库之一。文中讨论在SQL Server 2008中通过触发器技术实现数据完整性的机制,介绍触发器的概念、分类,重点论述DML触发器的实现过程,结合具体实例,设计DML触发器监督财务人员对资金的各种业务操作,包括插入、删除和更新记录,分析了触发器设计的基本步骤,并改进触发器设计,使审计表能够记录全部变化的数据,从而反映了触发器的应用在提高系统性能、维护数据库完整性、有效性等方面的强大功能。
文摘Most of the previous studies concerning checking the integrity constraints in distributed database derive simplified forms of the initial integrity constraints with the sufficiency property, since the sufficient test is known to be cheaper than the complete test and its initial integrity constraint as it involves less data to be transferred across the network and can always be evaluated at the target site （single site）. Their studies are limited as they depend strictly on the assumption that an update operation will be executed at a site where the relation specified in the update operation is located, which is not always true. Hence, the sufficient test, which is proven to be local test by previous study, is no longer appropriate. This paper proposes an approach to checking integrity constraints in a distributed database by utilizing as much as possible the local information stored at the target site. The proposed approach derives support tests as an alternative to the existing complete and sufficient tests proposed by previous researchers with the intention to increase the number of local checking regardless the location of the submitted update operation. Several analyses have been performed to evaluate the proposed approach, and the results show that support tests can benefit the distributed database, where local constraint checking can be achieved.
