第11章Chapter 11 Database Management.ppt

课件教案共享专家 /wear1981 大学英语 Computer English Chapter 11 Database Management *计算机专业英语 Chapter 11 Database Management * 课件教案共享专家 /wear1981 课件教案共享专家 /wear1981 课件教案共享专家 /wear1981 Key points:  useful terms and definitions of Database ManagementDifficult points:  Classification of the logical structuring techniques of DBMS 课件教案共享专家 /wear1981 Requirements: 1. Principle of easiest penetration 2. The kinds of computer security breaches 3. What is firewall 4. 了解英文摘要的写作技巧 课件教案共享专家 /wear1981 New Words Expressions: facilitate 使容易，促进 retrieval n. 检索 field n. 字段， record 记录， alphabetically 按字母顺序地 chronologically 按年代顺序排 break down v. 分解 build up 建造，装配，组成 encyclopedia n. 百科全书 reference n. 涉及，参考，引用 bibliography 书目，参考书目 periodical n. 期刊，杂志 literature n. 文献，著作 professional n. 专业人员，专家 11.1 Overview Abbreviations: 课件教案共享专家 /wear1981 A database consists of a file or a set of files. The information in these files may be broken down into records, each of which consists of one or more fields. Fields are the basic units of data storage, and each field typically contains information pertaining to one aspect or attribute of the entity described by the database. Using keywords and various sorting commands, users can rapidly search, rearrange, group, and select the fields in many records to retrieve or create reports on particular aggregates of data. 一个数据库由一个文件或文件集合组成。这些文件中的信息可分解成一个个记录，每个记录有一个或多个域。域是数据存储的基本单位，每个域一般含有由数据库描述的属于实体的一个方面或一个特性的信息。用户使用键盘和各种排序命令，能够快速查找、重排、分组并在查找的许多记录中选择相应的域，建立特定集上的报表。 11.1 Overview 课件教案共享专家 /wear1981 11.1 Overview Database records and files must be organized to allow retrieval of the information. Early systems were arranged sequentially (i.e., alphabetically, numerically, or chronologically); the development of direct-access storage devices made possible random access to data via indexes. Queries are the main way users retrieve databas