外文翻译----高级数据库应用.doc

毕业设计（论文） 外文翻译 题 目 高级数据库应用 专 业 信息与计算科学 班 级 学 生 指导教师 Advanced Database Applications The 1990s have seen significant changes in the computer industry. In database systems, we have seen the widespread acceptance of RDBMSs for traditional business applications, such as order processing, inventory control, banking, and airline reservations. However, existing RDBMSs have proven inadequate for applications whose needs are quite different from those of traditional business database applications. These applications include: ■ computer-aided design (CAD); ■ computer-aided manufacturing (CAM); ■ computer-aided software engineering (CASE); ■ office information systems (OIS) and multimedia systems; ■ digital publishing; ■ eographic information systems (GIS); ■ interactive and dynamic Web sites. Computer-aided design (CAD) A CAD database stores data relating to mechanical and electrical design covering, for example, buildings, aircraft, and integrated circuit chips. Designs of this type have some common characteristics: ■ Design data is characterized by a large number of types, each with a small number of instances. Conventional databases are typically the opposite. For example, the DreamHome database consists of only a dozen or so relations, although relations such as PropertyForRent, Client, and Viewing may contain thousands of tuples. ■ Designs may be very large, perhaps consisting of millions of parts, often with many interdependent subsystem designs. ■ The design is not static but evolves through time. When a design change occurs, its implications must be propagated through all design representations. The dynamic nature of design may mean that some actions cannot be foreseen at the beginning. ■ Updates are fat-reaching because of topological or functional relationships, tolerances, and so on. One change is likely to affect a large number of design objects. ■ Often, many design alternative