武汉理工大学数据库答案汇总

第一章：

1.1What is the purpose of a database?数据库的目的

The purpose of a database is to help people track(跟踪监测) of things.

1.2What is the most commonly used type of database?最常见的数据库类型

The most commonly used type of database is the relational database.

1.3Give an example of two related tables other than the example used in this book.

Use the STUDENT and GRADE tables in Figure 1-3 as an example pattern(模式) for your tables. Name the tables and columns using the conventions in this book.

给一个关联表的例子，参考1-3

Answer:

1.4For the tables you created in Review Question 1.3, what are the primary keys of

each table? Do you think that any of these primary keys could be surrogate(代理) keys?每张表的主码？这些主码可以是代理码吗？

Query1: StudentNumber

Query2: StudentNumber, RoomNumber

Yes, both.

1.5 Explain how the two tables you provided in Review Question 1.3 are related. Which table contains the foreign key, and what is the foreign key?

The primary key of Q1 were added to the Q2 with a primary key of StudentNumber to uniquely identify each row.

In Q2 StudentNumber and RoomNumber each now serves as a foreign key.

1.6 Show your two tables from Review Question 1.3 without the columns that represent the relationships. Explain how the value of your two tables is diminished(减少) without the relationships.在你的表中去掉代表关系的列，解释没有关系的表的value如何减少？

1.7 Define the terms data and information. Explain how the two terms differ.定义术语data和information,解释它俩的不同。

Answer: Data are recorded facts and numbers.

We can define information as:

Knowledge derived from data.

Data presented in a meaningful context.

Data processed by summing, ordering, averaging, grouping, comparing or other similar operations.

1.8 Give an example of information that could be determined using the two tables you provided in your answer to Review Question 1.3.

Anna Smith lives in 4-454 which the rent is 1300.

1.9 Give examples of a single-user database application and a multiuser database application other than the ones shown in Figure 1-5.举例子，单用户和多用户的数据库应用，除表1-5之外。

single-user: Cloud Service

multi-user: File Management System

1.10 What problem can occur when a database is processed by more than one user?

当数据库被不止一个用户处理会导致什么问题？

Answer: When more than one user employs a database application, these is always the chance that one user's work may interfere with other's.

1.11 Give an example of a database application that has hundreds of users and a

very large and complicated database. Use an example other than one in Figure 1-5.

举一个有成百上千个用户和一个庞大而复杂数据库的数据库应用，除表1-5以外。

Answer: Selection lesson system

选课系统

1.12 What is the purpose of the largest databases at e-commerce companies such

as ?

像亚马逊这样的电商公司有着最大的数据库的目的是什么？

Answer: The largest database are those that track customer browser behavior. (用来记录用户的浏览行为)