• Microsoft JDBC Driver 6.0 for SQL Server

    MICROSOFT JDBC DRIVER 6.0 FOR SQL SERVER 这些许可条款是微软公司(或您所在地的微软关联公司)与您之间达成的协议。请阅读条款内容。这些条款适用于上述软件,包括您用来接收该软件的介质(如果有)。这些条款也适用于微软为该软件提供的任何 • 更新 • 补充程序 • 基于 Internet 的服务,以及 • 支持服务

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  • 数据库系统概念(杨冬青)实践习题答案

    Practice Exercises 1.1 This chapter has described several major advantages of a database system. What are two disadvantages? Answer: Two disadvantages associated with database systems are listed below. a. Setupofthedatabasesystemrequiresmoreknowledge,money,skills, and time. b. The complexity of the database may result in poor performance. 1.2 List five ways in which the type declaration system of a language such as Java or C++ differs from the data definition language used in a database. Answer:

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  • 数据库系统概念(杨冬青)习题答案

    数据库系统概念(杨冬青)习题答案Chapter 1 provides a general overview of the nature and purpose of database systems. The most important concept in this chapter is that database systems allow data to be treated at a high level of abstraction. Thus, database systems differsignificantly from the file systemsand general purpose programming environments with which students are already familiar. Another important aspect of the chapter is to provide motivation for the use of database systems as opposed to application programs built on top of file systems. Thus, the chapter motivates what the student will be studying in the rest of the course. The idea of abstraction in database systems deserves emphasis throughout, not just in discussion of Section 1.3. The overview of the structure of databases is, of necessity, rather brief, and is meant only to give the student a rough idea of some of the concepts. The student may not initially be able to fully appreciate the concepts described here, but should be able to do so by the end of the course. The specifics of the E-R, relational, and object-oriented models are covered in later chapters. These models can be used in Chapter 1 to reinforce the concept of abstraction, with syntactic details deferred to later in the course. If students have already had a course in operating systems, it is worthwhile to point out how the OS and DBMS are related. It is useful also to differentiate between concurrency as it is taught in operating systems courses (with an orientation towardsfiles, processes,and physical resources)and database concurrency control (with an orientation towards granularity finer than the file level, recoverable transactions, and resources accessed associatively rather than physically). If students are familiar with a particular operating system, that OS’s approach to concurrent file access may be used for illustration.

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