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1.6 Advantages and Disadvantages of DBMSs （数据库的优点和缺点）
The database management system has promising potential advantages. （数据库管理系统具有广阔的潜在优势。）
promising /pr‘?misi?/ adj. someone or something that is promising seems likely to be very good or successful.
具有promising性质的人或者物似乎可能是非常好的或者成功的。
A school has honoured one of its brightest and most promising former pupils.
Unfortunately, there are also disadvantages. （不幸，也存在缺点。）
In this section, we examine these advantages and disadvantages. (在这一节，我们学习这些优点和缺点)
Advantages (优点)
The advantages of database management systems are listed in Table 1.2 . (图1.2列出了数据库管理系统的优点和缺点。)
TABLE 1.2 Advantages of DBMSs
|
Control of data redundancy 控制数据冗余 |
Economy of scale 经济规模 |
| Data consistency 数据的一致性 | Balance of conflicting requirement 相与冲突的需要平衡 |
| More information from the same amount of data 同样数量的数量有更多的信息量 |
Improved data accessibility and responsiveness 改进数据访问和响应 |
| sharing of data 数据共享 | Increased productivity 提高生产率 |
| Improved data integrity 数据完整性提高了 | |
| Improved security 安全性提高 | Improved maintenance through data independence 通过数据独立性改善维护 |
| Enforcement of standards 执行标准 | Increased concurrency 增加并发 |
| Improved backup and recovery services 改进了备份和恢复服务 |
Control of data redundancy (控制数据冗余)
As we discussed in Section 1.2, traditional file-based systems waste space by storing the same information in more than one file
(正如在1.2节讨论的，传统的基于文件系统浪费空间， 用于多于一个文件储存相同的信息。 )
For example, in Figure 1.5, we stored similar data for properties for rent and clients in both the Sales and Contracts Departments.
(例如， 在图1.5中， 在销售和合同两个部门，我们储存了相似的租金和客户属性。)
In constrast, the database approach attempts to eliminate the redundancy by integrating the files so that mulitiple copies of the same data are not stored.
eliminate /il‘mineit/ (eliminates, eliminating, eliminated)
1. [verb] V n, v n from n
To eliminate you do not want or need, means to remove it completely (Formal) ( To eliminate 你不想要或不需要的， 意思是完全移除它)
If you think you may be allergic to a food or drink, eliminate it from your diet. (如果你认为， 你可能过敏对于某种食物或饮料，把它从你的食谱里消除掉。)
2. [v-passive] be v-ed from n, be v-ed
When a person or team is eliminated from a competition, they are defeated and so take no further part in the competition.
(当某人或某一团队从一次竟赛中被淘汰，他们是失败的，并且不能参加下一次竟赛。)
If you are eliminated in the show-jumping then you are out of the complete competition.
(如果你在跳跃中被淘汰了，接着，你将对所有竟赛出局。)
3. [verb] v n
If someone says that they have eliminated an enemy, they mean that they have killed them.
(如果有人说，他们已经 eliminated了敌人，他们的意思是，他们已经杀死了敌人。)
By using the word ‘eliminate‘, they are trying to make the action sound more positive than if they used the word ‘kill‘.
（通过使用单词‘eliminate‘, 他们试图使动作听起来更积极一些，比起如果他们使用单词‘kill‘.）
He declared war on the government and urged right-wingers to eliminate opponents.
(他宣布，对政府战争，并敦促右翼分子消灭敌人。)
（相反，数据库方法试图消除冗余通过整合文件，以致于相同数据的多个副本不被存储。）
However, the database approach does not eliminate redundancy entirely, but controls the amount of redundancy inherent in the database.
inherent /inh‘er?nt/ [adj] usu ADJ n
The inherent qualities of something are the necessary and natural parts of it. (事物的内在品质，是它必要的和自然的组成部分。)
Stress is an inherent part of dieting.(压力是节食的内在组成部分。)
... the dangers inherent in an outbreak of war. (内战爆发的危险。)
（无论如何，数据库方式不能完全消除冗余，但是可以控制数据库内部的冗余数量。）Sometimes it is necessary to duplicate key data items to model relationship; at other times, it is duplicate some data items to improve performance. The reasons for controlled duplication will become clearer as you read the next few chapters.标签：
原文地址：http://www.cnblogs.com/666638zhangqiang/p/4798704.html
