第一章：1.1 What 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.1.2 What 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.1.3 Give 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1-3Answer:Query1：学生信息StudentNumberLastNameFirstNameEmailAddress1CookieSam1234OurU.edu2LaraMarcia1245OurU.edu3HarrisLou2453OurU.edu4GreeneGrace2563OurU.edu5SmithAnna4345OurU.eduQuery2：宿舍信息StudentNumberRoomNumberRoomInformationRent115-1231000233-6331100344-4661200422-4541100554-45413001.4 For 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: StudentNumberQuery2: StudentNumber, RoomNumberYes, 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 Servicemulti-user: File Management System1.10 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 users work may interfere with others.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 Amazon.com?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)1.13 How do the e-commerce companies use the databases discussed in Review Question 1.12?电商公司如何使用数据库？Answer: E-commerce companies use Web activity databases to determine which items on a Web page are popular and successful and which are not.1.14 How do digital dashboard and data mining applications differ from transaction processing applications?数字仪表板和数据挖掘应用程序在事务处理应用上有何不同？Answer: Digital dashboard and other reporting systems assess past and current performance. Data mining applications predict future performance. 1.15 Explain why a small database is not necessarily simpler than a large one.解释为什么一个小的数据库不一定比大的数据库简单？Answer: Supposed we have 2 company which are different in sales but have similar database. Though the difference in sale, both have the same kinds of data, about the same number of tables of data, about the same level of complexity in data relationships. Only the amount of data varies from one to the other. Thus, although a database for a small business may be small, it is not necessarily simple. (一句话，麻雀虽小五脏俱全)1.16 Explain the components in Figure 1-7.解释图1-7的成分要素A database system is defined to consist of five components:users, the database application, Structured Query Language (SQL), the database management system (DBMS), and the database.a. Users employ a database application to keep track of things. They use forms to read, enter, and query data, and they produce reports to convey information.b. A database application is a set of one or more computer programs that serves as an intermediary between the user and the DBMS.c. Structured Query Language (SQL), an internationally recognized standard language that is understood by all commercial DBMS products, in database processing and the fact that database applications typic