第11章计算机专业英语孙建忠讲述.ppt

Computer English Chapter 11 Database Management 11.1 Overview Database(sometimes spelled data base) is also called an electronic database, rerferring to any collections of data, or information, that is specially organized for rapid search and retrieval by a computer. Database are structured to facilitate the storage, retrieval, modification, and deletion of data in conjunction with various data-processing operations. Database can be stored on magnetic disk or tape, optical disk, or some other secondary storage device. 数据库（有时拼成 data base）也称为电子数据库，是指由计算机特别组织的用于快速查找和检索的任意的数据或信息集合。数据库与其他数据处理操作协同工作，其结构要有助于数据的存储、检索、修改和删除。数据库可存储在磁盘或磁带、光盘或某些辅助存储设备上。 11.1 Overview The many users of a large database must be able to manipulate the information within it quickly at any given time. Moreover, large business and other organizations tend to build up many independent files containing related and even overlapping data, and their data, processing activities often require the linking of data from several files. Several different types of database management systems have been developed to support these requirements: flat, hierarchical, network, relational, and object-oriented. 大型数据库的多个用户必须能在任意给定时间快速处理内部数据。而且，大型企业和其他组织倾向于建立许多独立的文件，其中包含相互关联的甚至重叠的数据，这些数据、处理活动经常需要和其他文件的数据相连。为满足这些要求，开发出各种不同类型的数据库管理系统，如：非结构化的数据库、层次型数据库、网络型数据库、关系型数据库、面向对象型数据库。 11.1 Overview The information in many database consists of natural-language texts of documents；number-oriented database primarily contain information such as statistics, tables, financial data, and raw scientific and technical data. Small database can be maintained on personal-computer systems and may be used by individuals at home. These and larger database have become increasingly important in business life. Typical commercial applications include airline reservations, production management, medical records in hospitals, and legal records of insurance companies. The largest database are usually maintained by governmental agencies, business o