共查询到20条相似文献,搜索用时 72 毫秒
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余军 《贵州教育学院学报》2008,19(12):44-46
数据完整性是指在同一数据库中的不同数据表中的相同数据应当保持一致性和可靠性。数据完整性是评价一个数据库设计质量的重要指标,它直接影响到整个数据库运行的性能。SQL Server在保障数据库完整方面提供了强大的机制,如何在SQL Server数据库中实现数据的完整性进行探讨。 相似文献
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介绍了GIS发展过程中出现的空间数据模型,以及不同空间数据模型的优缺点.对Geodatabase版本控制原理进行了分析说明,提出了使用版本控制来管理空间数据库的多用户并发操作、长事务处理,从而保证空间数据库的完整一致性.为建立和管理多用户的基于Geodatabase数据模型的空间数据库提供参考. 相似文献
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数据库应用于实验室管理已具有普遍性,但采用何种数据库进行管理,仍是困扰实验室管理者的难题.基于GNU(自由软件体系,即免费的及源代码开放)下的PostgreSQL数据库,比其他开放源代码的数据库(如msql、Mysql等)更为完整,将其应用于实验室管理,应是当今实验室管理综合性价比的最佳选择。 相似文献
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本在分析传统数据库的基础上,介绍了网络系统中数据库的组织和设计,数据库系统的各种组织方式,论述了ODBC技术和数据一致性的解决方案。 相似文献
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金栋林 《湖州师范学院学报》2000,22(6):51-54
介绍数据库容器的数据一致性规则,提出通过捕捉因违背数据库一致性规则而引发的错误进行相应控制的方法,从而为达到有效保证数据库数据一致性目的的表单设计思路,并给出相应的实例。 相似文献
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关系模型中的完整性是指数据库中数据的正确性和一致性。无论是单用户或多用户数据库,用户在操作中难免发生差错。如果对数据操作缺乏检验与约束,就难以保证数据的有效性。 相似文献
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目前,大数据对象在数据库存储时普遍采用存储路径的方式,由于使用这种方式文件系统不能自动备份和更新,既增加了管理人员的工作量,也极易破坏数据的一致性。要真正做到各类数据在数据库中安全管理,研究将大数据对象直接存储于数据库中的方法,是非常必要的。 相似文献
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非学历计算机信息管理系统是典型的管理系统软件,其开发主要包括后台数据库的建立和维护,以及前端应用程序的开发两个方面.对于前者要求建立数据一致性要强、数据完整性要好的数据库;对于后者要求应用程序的功能完备,容易使用等特点. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
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YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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GUO Bao-feng Xiao Da-wei 《重庆大学学报(英文版)》2005,4(3):129-133
Using virtual reality for interactive design gives a designer an intuitive vision of a design and allows the designer to achieve a viable, optimal solution in a timely manner. The article discusses the process of making the Virtual Reality System of the Humble Administrator's Garden. Translating building data to the Virtual Reality Modeling Language (VRML) is by far unsatisfactory. This creates a challenge for computer designers to do optimization to meet requirements. Five different approaches to optimize models have been presented in this paper. The other methods are to optimize VRML and to reduce the file size. This is done by keeping polygon counts to a minimum and by applying such techniques as object culling and level-ofdetail switching. 相似文献