1、 外文文献原稿和译文 原 稿 DATABASE A database may be defined as a collection interrelated data store together with as little redundancy as possible to serve one or more applications in an optimal fashion .the data are stored so that they are independent of programs which use the data .A common and controlled a
2、pproach is used in adding new data and in modifying and retrieving existing data within the data base .One system is said to contain a collection of database if they are entirely separate in structure . A database may be designed for batch processing , real-time processing ,or in-line processing .A
3、data base system involves application program, DBMS, and database. THE INTRODUCTION TO DATABASE MANAGEMENT SYSTEMS The term database is often to describe a collection of related files that is organized into an integrated structure that provides different people varied access to the same data. In man
4、y cases this resource is located in different files in different departments throughout the organization, often known only to the individuals who work with their specific portion of the total information. In these cases, the potential value of the information goes unrealized because a person in othe
5、r departments who may need it does not know it or it cannot be accessed efficiently. In an attempt to organize their information resources and provide for timely and efficient access, many companies have implemented databases. A database is a collection of related data. By data, we mean known facts
6、that can be recorded and that have implicit meaning. For example, the names, telephone numbers, and addresses of all the people you know. You may have recorded this data in an indexed address book, or you may have stored it on a diskette using a personal computer and software such as DBASE or Lotus
7、1-2-3. This is a collection of related data with an implicit meaning and hence is a database. The above definition of database is quite general. For example, we may consider the collection of words that made up this page of text to be usually more restricted. A database has the following implicit pr
8、operties: A database is a logically coherent collection of data with some inherent meaning. A random assortment of data cannot be referred to as a database. A database is designed, built, and populated with data for a specific purpose. It has an intended group of user and some preconceived applicati
9、ons in which these users are interested. A database represents some aspect of the real world, sometimes called the miniworld. Changes to the miniworld are reflected in the database. In other words, a database has some source from which data are derived, some degree of interaction with events in the
10、real world, and an audience that is actively interested in the contents of the database. A database management system (DBMS) is composed of three major parts: (1) a storage subsystem that stores and retrieves data in files； (2)a modeling and manipulation subsystem that provides the means with which
11、to organize the data and to add, delete, maintain, and update the data； and (3) an interface between the DBMS and its users. Several major trends are emerging that enhance the value and usefulness of database management systems. Managers who require more up-to-date information to make effective deci
12、sions. Customers who demand increasingly sophisticated information services and more current information about the status of their orders, invoices, and accounts. Users who find that they can develop custom applications with database systems in a fraction of the time it takes to use traditional prog
13、ramming languages. Organizations that discover information has a strategic value； they utilize their database systems to gain an edge over their competitors. A DBMS can organize, process, and present selected data elements from the database. This capability enables decision makers to search, probe,
14、and query data base contents in order to extract answers to nonrecurring and unplanned questions that arent available in regular reports. These questions might initially be vague and/or poorly defined, but people can “browse” through the database until they have the needed information. In short, the
15、 DBMS will “mange” the stored data items and assemble the needed items from the common database in response to the queries of those who arent programmers. In a file-oriented system, user needing special information may communicate their needs to a programmer, who, when time permits, will write one o
16、r more programs to extract the data and prepare the information. The availability of a DBMS, however, offers users a much faster alternative communications path. DATABASE QUERY If the DBMS provides a way to interactively enter and update the database ,as well as interrogate it ,this capability allow
17、s for managing personal database. However, it does not automatically leave an audit trail of actions and does not provide the kinds of controls necessary in a multi-user organization .There controls are only available when a set of application programs is customized for each data entry and updating
18、function. Software for personal computers that perform some of the DBMS functions has been very popular .Individuals for personal information storage and processing intended personal computers for us .Small enterprises, professionals like doctors, architects, engineers, lawyers and so on have also u
19、sed these machines extensively. By the nature of intended usage ,database system on there machines are except from several of the requirements of full-fledged database systems. Since data sharing is not intended, concurrent operations even less so ,the software can be less complex .Security and inte
20、grity maintenance are de-emphasized or absent .as data volumes will be small, performance efficiency is also less important .In fact, the only aspect of a database system that is important is data independence. Data independence ,as stated earlier ,means that application programs and user queries need not recognize physical organization of data on secondary storage. The importance of this aspect , particularly for the personal computer user ,is that this greatly simplifies database usage . The user can store ,access and manipulate data at a
