第三单元大学英语英语翻译_第三单元英语翻译
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Organizing Data in a Traditional File
Environment
An effective information system provides users with timely, accurate, and relevant information.This information is stored in computer files.When the files are properly arranged and maintained, users can easily acce and retrieve the information they need.传统环境下的数据组织
一个高效的信息系统应向使用者提供及时、准确以及相关的信息。信息存储在系统的文件中。正确地整理和维护文件，可以使用户很容易地检索到他们所需要的信息。
You can appreciate the importance of file management if you have ever written a term paper using 3×5 index cards.No matter how efficient your storage device(a metal box or a rubber band), if you organize the cards randomly your term paper will have little or no organization.如果你在撰写学期论文时曾经使用过3×5索引卡，你会体会到文件管理的重要性。不管你的存储设备（一个金属盒或一个皮筋）效率如何,如果你随意地组织你的卡片,你的学期论文将会缺乏组织性
Given enough time, you could put the cards in order, but your system would be more efficient if you set up your organizational scheme early on.If your scheme is flexible enough and well documented, you can extend it to account for any changes in your viewpoint as you write your paper.如果有足够的时间，你可以将卡片按次序放置，但是如果你早点创建你自己的组织方案，你的系统会做得更有效。如果你的方案足够的灵活并且文档也很齐全，那么在你撰写论文时，可以利用它来说明观点中的任何变化。
The same need for file organization applies to firms.Well-managed, carefully arranged files make it easy to obtain data for busine decisions, whereas poorly managed files lead to chaos in information proceing high costs, poor performance, and little, if any, flexibility.Despite the use of excellent hardware and software, many organizations have inefficient information systems because of poor file management.公司同样也需要组织文件。组织良好，认真安排的文件可以使商业决策获取数据变得更容易，而组织混乱的文件只能导致信息处理紊乱、成本高、性能差并且灵活性低。尽管使用优秀的硬件和软件，但由于文件组织得不好，很多组织的信息系统的效率还是很低。
File Organization Terms and Concepts A computer system organizes data in hierarchy that starts with bits and bytes and progrees to fields, records, files, and databases.A bit represents the smallest unit of data a computer can handle.文件组织术语及概念
计算机系统按层次组织数据，位、字节、数据项、记录、文件和数据库。位代表计算机中最小的数据单位。
A group of bits, called a byte, represents a single character, which can be a letter, a number, or another symbol.A grouping of characters into a word, a group of words, or a complete number(such as a person’s name or age), is called a field.一组位，叫做一个字节，表示一个独立的字，它可以是一个字母、一个数字或其它的符号。一组字组成一个词、一组词或一个纯数字（例如一个人的名字或年龄）叫做一个字段。
A group of related fields, such as the student’s name, the course taken, the date, and the grade, comprises a record;a group of records of the same type is called a file.For instance, the student records could constitute a course file.一组相关的字段，例如学生的姓名、所选的课程、日期、年级，组成一个记录；一组相同类型的记录被称为文件。例如，学生记录可以构成一个课程文件。
A group of related files makes up a database.The student course file could be grouped with files on student’s personal histories and financial backgrounds to create a student database.一组相关的文件组成一个数据库。学生课程文件可以和学生个人履历文件、个人经济情况文件共同创建一个学生数据库。
A record describes an entity.An entity is a person, place, thing, or event on which we maintain information.An order is a typical entity in a sales order file, which maintains information on a firm’s sales orders.Each characteristic or quality describing a particular entity is called an attribute.一个记录描述了一个实体。一个实体可以是一个人、一个地方、一个东西或一件事情，我们维护与它们有关的信息。销售订单文件提供一个公司销售订单信息，在销售订单文件中，一个订单是一个典型的实体。
For example, order number, order date, order amount, item number, and item quantity would each be an attribute of the entity order.The specific values that these attributes can have can be found in the fields of the record describing the entity order.每个用来描述具体实体的特质或特征的叫做属性。例如，订单号、订货日期、订货量、产品代码和产品数量每一个都是实体订单的一个属性。这些属性的具体取值可以在描述实体订单的记录中的字段里找到。
Every record in a file should contain at least one field that uniquely identifies that record so that the record can be retrieved, update, or sorted.This identifier field is called a key field.An example of a key field is the order number for the order record or an employee number or social security number for a personnel record(containing employee data such as the employees’ name, age, addre, job title, and so forth).文件中的每一条记录至少包含一个能被唯一识别的数据字段，这样记录可被检索、更新或分类。这个标识字段叫做关键字段。举个关键字段的例子,如订单号是订单记录的关键字段，员工编号或社会保险号是一个个人记录（包括员工数据，例如员工的名字、年龄、住址、工作职别等等）的关键字段。
Acceing Records from Computer Files
Computer systems store files on secondary storage devices.Records can be arranged in several ways on storage media, and the arrangement determines the manner in which individual records can be acceed or retrieved.从计算机文件中存取记录
计算机系统将文件存储在外存设备中。记录以多种方式存放在存储介质中，而且存放方式决定了单个记录被存取或检索的方式。
One way to organize records is sequentially.In sequential file organization, data records must be retrieved in the same physical sequence in which they are stored.In contrast, direct or random file organization allows users to acce records in any sequence they desire, without regard to actual physical order on the storage media.一种组织记录的方式是有序的。在按顺序组织的文件中，数据记录的检索顺序必须与数据的存储顺序相同。相反，不考虑存取介质的物理顺序，直接或随机存取文件允许用户以任何他们想要的顺序存取文件。
Sequential file organization is the only file organization method that can be used on magnetic tape.This file organization method is no longer popular, but some organizations still use it for batch proceing applications in which they acce and proce each record sequentially.顺序文件组织是唯一的一种可以用在磁带上的文件组织方式。这种文件组织方式已不再流行了，但是一些组织仍然使用它来进行批处理，这些处理对每一条记录依次进行存储和处理。
A typical application using sequential files is payroll, in which all employees in a firm must be paid one by one and iued a check.Direct or random file organization is utilized with magnetic disk technology(although records can be stored sequentially on disk if desired).Most computer applications today utilize some method of direct file organization.顺序文件的一个典型应用是工资单，必须依次地对工资单中的所有公司职员支付工资和支票。直接存取或随机存取文件组织方式可用于磁盘技术（但是，如果愿意的话，磁盘中的记录可以按顺序存储）。
Problems with the Traditional File Environment
Most organizations began information proceing on a small scale, automating one application at a time.Systems tended to grow independently, and not according to some grand plan.Each functional area tended to develop systems in isolation from other functional areas.Accounting, finance, manufacturing, human resources, and marketing all developed their own systems and data files.传统文件环境存在的问题
大多数组织每次进行的都是小规模的、自动化的信息处理。系统越来越具有独立性，并且不再采用大型的方案。每个功能区的开发都试图孤立于其它模块。会计、金融、生产、人力资源和销售均开发各自的系统和数据文件。
Each application, of course, required its own files and its own computer program to operate.For example, the human resources functional area might have a personnel master file, a payroll file, a medical insurance file, a pension file, a mailing list file, and so forth until tens, perhaps hundreds, of files and programs existed.当然，每个应用都需要自己的文件和计算机系统。例如，人力资源功能区可能需要一个人事主文件、一个工资文件、一个医保文件、一个退休金文件、一个邮件发送清单文件等等，几十个甚至上百个文件或程序。
In the company as a whole, this proce led to multiple master files created, maintained, and operated by separate divisions or departments.就整个公司来说，这个过程会导致多种主要文件的创建、维护，并被不同的部门使用。
There are names for this situation: traditional file environment;the flat file organization(because most of the data are organized in flat files);and the data file approach(because the data and busine logic are tied to specific files and related programs).By any name, the situation results in growing inefficiency and complexity.对这种情况的叫法有：传统文件环境、平面文件组织（因为大部分的数据组织在平面文件里）、数据文件方式（因为数据和事务逻辑被捆绑于具体的文件和相关的程序中）。无论是哪个名字，这种环境的结果就是低效和复杂性越来越大。
As this proce goes on for five or ten years, the organization is saddled with hundreds of programs and applications, with no one who knows what they do, what data they use, and who is using the data.当这种处理方法使用了五或十年，组织已经承载了上百个程序和应用软件，没有人知道这些程序和软件做什么，用什么数据，并且谁在使用数据。
The organization is collecting the same information in far too many files.The resulting problems are data redundancy, program-data dependence, inflexibility, poor data security, and inability to share data among applications.组织可以从多个文件中搜集同一个信息。导致的问题就是数据冗余、程序与数据间相依赖、非灵活性、缺乏数据安全性和应用软件之间无法共享数据。
Data Redundancy and Confusion
Data redundancy is the presence of duplicate data in multiple data files.Data redundancy occurs when different divisions, functional areas, and groups in an organization independently collect the same piece of information.For instance, within the commercial loans division of a bank, the marketing and credit information functions might collect the same customer information.数据冗余和混乱
数据冗余表现为完全一样的数据存放在多个数据文件中。当一个组织中不同的部门、功能和团体独立地搜集相同部分信息时就会发生数据冗余。例如，在一个银行的商业贷款部门里，市场和借贷信息功能可能搜集相同的客户信息。
Because it is collected and maintained in so many different places, the same data item may have different meanings in different parts of the organization.Simple data items such as the fiscal year, employee identification, and product code can take on different meanings as programmers and analysts work in isolation on different applications.由于信息的搜集和维护是在不同的地方进行的，所以相同的数据项会在组织中不同的部分有不同的含义。当不同的应用软件的程序员和分析工作是相互孤立的，简单的数据项，例如会计年度、员工身份证明和产品编码会表现出不同的意思。
Program-Data Dependence
Program-data dependence is the tight relationship between data stored in files and the specific programs required to update and maintain those files.Every computer program has to describe the location and nature of the data with which it works.程序与数据间相依赖
程序和数据之间的依赖是指存储在文件中的数据和用来更新及维护这些文件的具体的程序间存在紧密的关系。每个计算机程序都必须对它使用的数据的位置和属性进行描述。
In a traditional file environment, any change in data requires a change in all programs that acce the data.Changes, for instance, in tax rates or ZIP-code length require changes in programs.Such programming changes may cost millions of dollars to implement in programs that require the revised data.在传统文件环境中，数据的任何更改要求所有存取这一数据的程序发生改变。例如，税率或邮政编码长度的变化要求程序也要随之变动。这种对修改了数据的程序进行设计上的改变可能会花费几百万美元。
Lack of Flexibility
A traditional file system can deliver routine scheduled reports after extensive programming efforts, but it cannot deliver ad hoc reports or respond unanticipated information requirements in a timely fashion..缺乏灵活性
一个传统文件系统在大量的程序设计工作后会提供常规的日程安排报告，但是它不能提供临时的报告或及时回应事先无法预料到的信息需求。
The information required by ad hoc requests is somewhere in the system but too expensive to retrieve.Several programmers would have to work for weeks to put together the required data items in a new file.临时请求所需要的信息存储在系统某处，但由于花费高而无法获取。几个程序员需要花费数周的时间将所需的数据项放到一个新文件中。
Poor Security
Because there is little control or management of data, acce to and diemination of information are virtually out of control.What limits on acce exist tend to be the result of habit and tradition, as well as of the sheer difficulty of finding information.缺乏安全性
由于对数据的控制和管理太少，信息的存取和传播实际上是不被控制的。现有的存取限制是由习惯和惯例所造就的，同样也造就了寻找信息的异常艰难。
Lack of Data-Sharing and Availability
The lack of control over acce to data in this confused environment does not make it easy for people to obtain information.Because pieces of information in different files and different parts of the organization cannot be related to one another, it is virtually impoible for information to be shared or acceed in a timely manner.缺乏数据共享和有效性
在这种混乱的环境里，对数据的存取缺乏控制使得人们很难获取信息。因为不同文件中的信息和组织的不同部分不能联系起来，所以信息无法及时共享或存取。
The Database Environment Database technology can cut through many of the problems created by traditional file organization.A more rigorous definition of a database is collection of data organized to serve many applications efficiently by centralizing the data and minimizing redundant data.数据库环境
数据库技术可以解决很多有传统文件组织方式引发的问题。对数据库更严密的定义是通过集中数据和减少多余的数据，有效地向应用软件提供组织过的数据集合。
Rather than storing data in separate files for each application, data are stored physically to appear to users as being stored in only one location.数据的物理存放要让用户觉着数据被存放在唯一的一个地方，而不是存储到每个应用程序所需的相互独立的文件上。
A single database services multiple applications.For example, instead of a corporation storing employee data in separate information systems and separate files for personnel, payroll, and benefits, the corporation could create a single common human resources database.一个数据库可以为多个应用程序提供服务。例如，将员工数据存储在相互独立的信息系统和相互独立的员工文件、工资文件和保险金文件中的一个替代做法是，公司可以创建一个通用的人力资源数据库。
Database Management Systems
A database management system(DBMS)is simply the software that permits an organization to centralize data, manage them efficiently, and provide acce to the stored data by application programs.数据库管理系统
数据库管理系统（DBMS）就是一个简单的软件，它允许一个组织集成数据、有效管理数据并且通过应用程序提供对存储数据的存取。
The DBMS acts as an interface between application programs and the physical data files.When the application program calls for data item such as gro pay, the DBMS finds this item in the database and presents it to the application program.DBMS在应用程序和物理数据文件间扮演接口的角色。当应用程序需要如工资总额的数据项，DBMS在数据库中查找这一数据项并将它提交给应用程序。
Using traditional data files the programmer would have to define the data and then tell the computer where they were.A DBMS eliminates most of the data definition statements found in traditional programs.A database management system has three components: A data definition language A data manipulation language A data dictionary 使用传统的数据文件，程序员不得不定义数据并且告诉计算机它们在那儿。一个DBMS会去除大部分传统程序中的数据定义声明。
一个数据库管理系统包含三个组成部分： 数据定义语言 数据操作语言 数据字典
The data definition language is the formal language used by programmers to specify the content and structure of the database.The data definition language defines each data element as it appears in the database before that data element is translated into the forms required by application programs.数据定义语言是程序员用来详述数据库内容和结构的形式语言。在数据元素被翻译成应用程序所需要的形式之前，数据定义语言定义了数据库中的每一个数据元素。
Most DBMS have a specialized language called a data manipulation language that is used in conjunction with some conventional third-or fourth-generation programming languages to manipulate the data in the database.This language contains commands that permit end users and programming specialists to extract data from the database to satisfy information requests and develop applications.大部分DBMS有一种叫做数据操作语言的专用语言，它和传统的第三代或第四代程序语言结合起来操作数据库中的数据。这种语言包括允许终端用户和程序设计专家从数据库中提取数据来满足信息需求和应用开发的命令。
The most prominent data manipulation language today is Structured Query Language, or SQL.Complex programming tasks cannot be performed efficiently with typical data manipulation languages.However, most mainframe DBMS are compatible with COBOL, FORTRAN, and other third-generation programming languages, permitting greater proceing efficiency and flexibility.现今，最杰出的数据操作语言是结构化查询语言，或者叫SQL。使用典型的数据操作语言，复杂的编程任务无法被高效率地执行。然而大部分中央处理机的DBMS与COBOL, FORTRAN及其他第三代编程语言相兼容，这就使得处理更高效和更灵活。
The third element of a DBMS is a data dictionary.This is an automated or manual file that stores definitions of data elements and data characteristics such as usage, physical representation, ownership(who in the organization is responsible for maintaining the data), authorization, and security.Many data dictionaries can produce lists and reports of data utilization, groupings, program locations, and so on.DBMS的第三个元素是数据字典。这是一个自动或手工的文件，存储了对数据元素和数据属性的定义，例如使用、物理表示、所有权（组织中谁负责维护数据）、授权和安全。很多数据字典可以提供数据使用、分组、程序存储位置等内容的列表和报告。
By creating an inventory of data contained in the database, the data dictionary serves as an important data management tool.For instance, busine users could consult the dictionary to find out exactly what pieces of data are maintained for the sales or marketing function or even to determine all the information maintained by the entire enterprise.由于建立了一个数据库中数据的清单，数据字典成为一个重要的数据管理工具。例如，商业用户可以翻阅字典来正确地查找出用于销售或市场功能的数据或者甚至支配整个公司的所有信息。
The dictionary could supply busine users with the name, format, and specifications required to acce data for reports.Technical staff could use the dictionary to determine what data elements and files must be changed if a program is changed.字典可以为商业用户提供名字、格式和说明，以获取报告所需数据。技术员工可以利用字典来决定如果一个程序发生了改动,那么什么样的数据元素和文件也必须被改变。
Most data dictionaries are entirely paive;they simply report.More advanced types are active;changes in the dictionary can be automatically utilized by related programs.For instance, to change ZIP codes from five to nine digits, one could simply enter the change in the dictionary without having to modify and recompile all application programs using ZIP codes.大部分的字典是完全被动式的；它们只不过是报告。更高类型的字典是主动的；相关程序可自动地使用字典中的变化。例如，将邮政编码由五位改为九位，一个人可以简单地在字典中记录这一改变，不必修改和重新编译所有使用邮政编码的程序。
In an ideal database environment, the data in the database are defined only once and used for all applications whose data reside in the database, thereby eliminating data redundancy and inconsistency.Application programs, which are written using a combination of the data manipulation language of the DBMS and a conventional programming language, request data elements from the database.在一个理想的数据库环境里，数据库中的数据只被定义一次就可以被所有的应用软件使用，因此可以消除数据的冗余和不一致性。结合DBMS的数据操作语言和常规程序语言编写的应用程序需要数据库中的数据元素。
Data elements called for by the application programs are found and delivered by the DBMS.The programmer does not have to specify in detail how or where the data are to be found.应用程序需要的数据元素可由DBMS查找和传递。程序员不必详述查找数据的位置和方式。
Use of a DBMS can reduce program-data dependence along with program development and maintenance costs.Acce and availability of information can be increased because users and programmers can perform ad hoc queries of data in the database.The DBMS allows the organization to centrally manage data, utilization, and security.使用DBMS除了减少程序的开发和维护费用，还可以减少程序和数据间的依赖。由于用户和程序员可以对数据库中的数据进行随机查询，信息的可获性和可用性得到提高。DBMS允许组织集中管理数据、应用和安全。
New Words(1)New Words(2)New Words(3)New Words(4)New Words(5)New Words(6)Phrases(1)Phrases(2)Abbreviations Questions for Discuion Why do we need file organization? How to acce records from computer files? Which problems exist in the traditional file environment? What is DBMS? How does DBMS resolve problems in the traditional file environment? Translation for Reference
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