数据库管理系统中英文对照

在刷新文件时可能出现问题。

假设一个用户申请文件中的一个数

据并修改它，

同时另外一个用户也申请这个数据并修改它，

解决这种问题的方法

叫做数据锁定，即第一个申请使其他申请处于等待状态， 直到完成第一个申请，

其他用户可以读取这个数据，但不能修改。

数据库服务器是一个通过网络为数据库申请提供服务的软件，

例如，

假设某

个用户在他的个人计算机上输入了一个数据查询 命令，

如果应用程序按照客户机

/

服务 器模型设计，

那么个人计算机上的查询语言通过网络传送数据库服务器上，

当发现数据时发出通知。

在工程界也有许多分布式 数据库的例子，

如

SUN

公司的网络文 件系统

（

NFS

）

被应用到计算机辅助工程应用程序中，

将数据分散到由

SU N

工作站组成的网络上

的不同硬盘之间。

分布式数据库是革命性的进步，

因为把数据存放在被使用位 置上是很合乎常

理的。例如一个大公司不同部门之间的计算机，应该将数据存储在本地， 然而，

当被授权的管理人员需要整理部门数据时，

数据应该能够 被访问。

数据库信息系

统软件将保护数据库的安全性和完整性，

对用户而言，

分布式数据库和非分布式

数据库看起来没有什么差别。

原文

Database Management Systems( 3th Edition ),Wiley ,2004, 5-12

A introduction to Database Management System

Raghu Ramakrishnan

4

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A database (sometimes spelled data base) is also called an electronic database

,

referring to any collection of data, or information, that is specially organized for rapid

search and retrieval by a computer. Databases are structured to facilitate the storage,

retrieval

,

modification,

and

deletion

of

data

in

conjunction

with

various

data-processing operations .Databases can be stored on magnetic disk or tape, optical

disk, or some other secondary storage device.

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

aggregate of data.

Complex

data

relationships

and

linkages

may

be

found

in

all

but

the

simplest

databases .The

system

software

package

that

handles

the

difficult

tasks

associated

with

creating

,accessing,

and

maintaining

database

records

is

called

a

database

management system(DBMS).The programs in a DBMS package establish an interface

between

the

database

itself

and

the

users

of

the

database..

(These

users

may

be

applications programmers, managers and others with information needs, and various

OS programs.)

A

DBMS

can

organize,

process,

and

present

selected

data

elements

form

the

database.

This

capability

enables

decision

makers

to

search,

probe,

and

query

database contents in order to extract answers to nonrecurring and unplanned questions

that

aren

’

t

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 DBMS will

“< /p>

manage

”

the stored data items and

assemble the needed items from the common database in response to the queries of

those who aren

’

t

programmers.

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 to organize the data and