数据库基本概念
Chapter Summary
1. The Database Management System (DBMS) is now underlying framework of the information system and has fundamentally changed the way in which many organizations operate.
现在，数据库管理系统是信息系统的底层架构， 从基础上改了许多组织的操作方式。
The database system remains a very active research area and many significant problems remain.
数据库系统仍然是一块非常活跃的区域， 仍然存在许多重要的问题。
2. The predecessor to the DBMS was the file-based system, which is a collection of application programs that perform
services for the end-users, usually the production of reports.
数据库的前身是文件系统， 一种为终端用户执行报务的应用程序的集合， 通常是报文生成。
Each program defines and manages its own data.
每一个程序定义和管理它自己的数据。
Although the file-based system was a great improvement over the manual filing system, it still has significant
problems, mainly the amount of data redundancy present and program-- data dependence.
虽然，基于文件系统是一个重要的提高对于手工文件系统，它仍然有重要的问题，主要是出现数据冗余的数量和程序---数据的独立性。
3.The database approach emerged to resolve the problems with the file-based approach.
emerge /im'ædʒ/ (emerges, emerging, emerged)
1.[verb] To emerge means to come out from an enclosed or dark space such as a room or a vechile, or from a position where you could not be seen.
To emerge 意思是从一个关闭的或者黑暗的空间出来，例如一个房间或者一量车， 或者从一个地方，那里你看不到东西。
Richard was waiting outside the door as she emerge .. 由于她的出现，里查德正候在门外。
The postman emerged from his Van soaked to the skin.浑身湿透的邮递员从他的面包车出现
...holes made by the emerging adult 即将成年的人所作的洞。
2. [verb] V from n
If you emerge from a difficult or bad experience, you come to the end of it.
如果你从一个次困难或者不好的经历中emerge, 你将使它结束。
There is growing evidence that the economy is at last emerging from recession.
有越来越多的证据表明， 经济最终摆脱衰退。
3. [verb] v, it v that, v-ing
If a fact or result emerges from a period of thought, discussion, or investigation, it becomes known as a result of it.
如果一个事实或者结果emerges 来自于一段时间的思考、讨论、或者调查，它作为自身的结果而知名。
The emerging caution over number is perhaps only to be expected.
在警戒值以上出现告警也许仅仅是一种期待。
It soon emerged that neither the July nor August mortgage repayment had been collected.
不久，将出现，既不是七月也不是八月，按揭还款已经被收集起来...
... the growing corruption that has emerged in the past few years...
...越来越多的腐败，在过去几年已经出现...
4.[verb] v, v-ing
When something such as an organization or an industry emerges, it comes into existence
当一些事情，诸如一个组织或者一个工业之类的出现，它已经存在。
... the new republic that emerged in October 1917...
在1917年10月，新的共各制的兴起...
...the emergying democracies of Eastern Europe.
东欧出现新兴的民主政体。
4. [verb] v as n. v
If something or someone emerges as particular thing, they become recognized as that thing.
如果某些事情或者某些人出现作为一件特别的事情，他们变得被认可因为那件事情。
New leaders have emerged. 新的领导已经上任。
A database is a share collection of logically related data and a description of this data, designed to meet the
information needs of an organization.
数据库是一个逻辑相关数据的集合，这种数据的描述， 被设计用来处理一个公司所需的信息。
A DBMS is software system that enables users to define, create, or maintain, and control access to database.
DBMS 是一个软件，允许用户定义，制作，或者维护，和控制录入数据库。
An application program is a computer program that interacts with the database by issuing an appropriate request
(typically a SQL statement) to the DBMS.
一个应用程序是一个计算机程序，和数据库交互操作， 通过提议一个合适的查询（典型的是一个SQL 语句）征对于DBMS.
The more inclusive term database system is used to define a collection of application programs that interact with the
database along with the DBMS and Database itself.
inclusive /inkl'u:siv/ 1. [adj] oft adj of n
If a price is inclusive, it includes all the charges connected with the goods or services offered. If a price is inclusive of postage and packing, it inclusive charge of this.
...all prices are inclusive of delivery
... an inclusive price of $32.94
inclusive is also adv.
... a special introductory offer of $ 5995 fully inclusive
2. [adj] n adj
After stating the first and last item in a set of things, you can add inclusive to make it clear that the items stated are included in the set.
Training will commence on 5 October, running from Tuesday to Saturday inclusive.
3. [adj] If you describe a group or organization as inclusive, you mean that it allows all kinds of people to belong to it, rather than just one kind of person.
The acadamy is far more inclusive now than it used to be.
All access to the database is through the DBMS.
所有数据库的入口是通过DBMS.
The DBMS provides a Data Definition Laguage (DDL), which allows users to define the database, and a Data Manipulation
Language (DML), which allows users to insert, update, delete, and retrieve data from the database.
DBMS 提供了一个数据定义语言， 允许用户定义数据库， 和一个数据处理语言，允许用户插入、删除、检索数据从数据库。
The DBMS provides controlled access to the database.
DBMS提供了针对数据库的控制路径。
It provides security, integrity, concurrency and recovery control, and a user-accessible catalog.
它提供了安全，完整型，一致性和还原控制，和一个用户认可目录。
It also procvides a view mechanism to simplify the data that users have to deal with.
它也提供了一个视窗机制，用户必须处理的简单数据。
The DBMS environment consists of hardware (the compter), software (the DBMS, operating system, and applications programs),
data, procedures, and people.
DBMS 环境包括硬件（计算机），软件（DBMS,操作系统、应用程序），数据，程序，和人。
The people include data and database administrators, database designers, application developers, and end-users.
人包括数据和数据库管理员，数据库设计者， 应用程序开发员，和终端用户。
The roots of the DBMS lie in file-based systems.
数据库的根源于基于文件系统。
The hierarchical and CODASYL systems represent the first generation of DBMSs.
The hierarchical model is typified by IMS (Information Mangement System) and Network or CODASYL model by IDS(Integrated
Data Store), both developed in the mid-1960s.
The related model, proposed by E.F.codd in 1970, represents the second generation of DBMSs.
关系模型， 在1970年E.F.Codd 教授声明， 代表着第二代DBMS。
It has had a fundamental effect on the DBMS community and there are now over one hundred relational DBMSs.
The third generation of DBMSs are represented by the Object-Relational DBMS and Object-Oriented DBMS.
第三代DBMS是以面象关系DBMS和面像对象的DBMS为代表。
Some advantages of the database approach include control of data redundancy, data consistency, sharing of data, and
iproved security and integrity.
数据库方法的优点包括： 控制数据冗余，数据的一致性、数据共享、和提高了安全性和完整性。
Some disadvantages include complexity, cost, reduced performance, and higher impact of a failure.
一些缺点包括： 复杂、减少了执行力、还有更高的失误影响
