武汉理工大学数据库答案汇总精要.docx

第一章：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.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. 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StudentNumberLastNameFirstNameEmailAddress1CookieSam1234@OurU.edu2LaraMarcia1245@OurU.edu3HarrisLou2453@OurU.edu4GreeneGrace2563@OurU.edu5SmithAnna4345@OurU.eduQuery2：宿舍信息StudentNumberRoomNumberRoomInformationRent115-1231000233-6331100344-4661200422-4541100554-4541300For 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 y