Tutorial on the principle and application of database system (008) -- exercises on database related concepts

Database system principle and Application Tutorial （008）—— Database related concept exercises

One 、 Short answer

1、 What is data ？ What are the characteristics of the data ？

answer ：
（1） Data is a symbolic record used to describe things .
（2） Data has the following characteristics ：
A） Data is the reflection of the attributes of things .
B） Data is constrained by data type and value range .
C） Data has carrier and manifestation .

2、 What are the main tasks of data management ？

answer ： Data management mainly includes the following aspects ：
（1） Organize and save data ;
（2） Manage and maintain data ;
（3） Data query and statistics .

3、 What is a database ？ What are the characteristics of the data in the database ？

answer ：
（1） The database is stored in the computer for a long time , Organized 、 Sharable data set . Database is a new method and technology of data management , He can organize data more reasonably 、 More convenient maintenance data 、 Tighter control of data and more efficient use of data .

（2） The data in the database has the following characteristics ：
A） The data in the database has a certain organizational structure , Can be Shared .
B） The data in the database has integrity , It is a reflection of the attributes of things managed .

4、 What is database management system ？ What are its main functions ？

answer ：
（1） Database management system is a layer of data management software between user application and operating system , Is the core component of the database system , Manage and maintain the database .

（2）DBMS The functions are as follows ：
A） Define database ;
B） Manipulating databases ;
C） Control database ;
D） Fault recovery ;
E） The data transfer .

Defining and manipulating databases is DBMS Basic functions of .

5、 The database system consists of those parts ？

answer ：DBS By database 、 Database management system 、 Application system 、 Users of the database system 、 Database administrators consist of .

6、 Detail the three-level schema structure of the database system .

answer ： The three-level schema of database includes logical schema 、 External mode 、 Internal mode .

（1） A logical schema is a description of the overall logical structure and characteristics of data in a database . Logical mode is to reduce data redundancy 、 Implement data sharing , A unified global data view obtained by integrating the data of all users .

（2） External mode is a description of the logical structure and characteristics of the data involved in each user or program . External mode can facilitate users to use data , Improve data security .

（3） Internal schema is the internal representation and underlying description of data . Internal mode can organize the global logical mode into the optimal structure and save it in the computer , To improve the efficiency of data access , Improve the performance index of the system .

7、 What is data independence ？ How does the database system ensure the independence of data ？

answer ： Data independence refers to the degree of dependency between applications and data . Data independence is divided into logical independence and physical independence .
A） The logical independence of data refers to the dependence of applications on the global logical structure of data . When the global logical structure of the database system changes , If the corresponding application does not need to make any changes , It shows that the logical independence of data is very high .
B） The physical independence of data refers to the dependence of applications on the data storage structure . When the physical structure of the data changes , If the corresponding application does not need to be modified , It indicates that the physical independence of the data is very high .

8、 Describe the secondary image technology of database and its function .

answer ：
（1） In order to achieve transparency between users and data , The database management system provides a secondary image ： External mode / Pattern image ; Pattern / Internal mode image .

（2） The secondary image ensures that the data in the database system can have high logical independence and physical independence .
A） External mode / Pattern image ： External mode / Pattern mapping defines the correspondence between external patterns and patterns , External mode / Schema images are generally described in external schemas . When the mode changes ,DBA You can change the external mode by modifying the image . Because the application is designed according to the external pattern , As long as the external mode does not change , The application does not need to be modified . External mode / Schema mapping technology not only establishes the corresponding relationship between user database and logical database , At the same time, it also ensures the logical independence of data .
B） Pattern / Internal mode image ： Pattern / The inner schema image defines the corresponding relationship between logical schema and inner schema . When the storage structure of the database changes ,DBA You can modify the mode / The mapping between internal schemas keeps the data schema unchanged . Because users or programs use data according to the logical mode of data , So as long as the data pattern remains the same , Users can still use the data the same way , The program does not need to be modified , Ensure the physical independence of data .

Two 、 choice question

1、 Which of the following options is not a basic function of a database management system ？（ D ）

（A） Database definition （B） The establishment and maintenance of database （C） Database access
（D） Communication between database and other software systems in the network

2、 In the three-level schema structure of the database , The internal mode has （ A ） individual , The logical modes are （A） individual , External mode has （D） individual ？

（A）1 individual （B）2 individual （C）3 individual （D） Any number of

3、 In database management system , Which module is not a database access function module ？（A）

（A） Transaction manager module （B） Data updater module （C） Interactive query module （D） Query handler module

4、 In the following description , Those are not the main features of database technology ？（D）

（A） The structure of data （B） Data redundancy is small （C） High data independence （D） Standardization of procedures

5、（B） It is organized according to a certain data model 、 Long term storage in the computer 、 Sharable data set .

（A） Database system （B） database （C） relational database （D） Database management system

6、 Which of the following is not the control function of the database management system ？（B）

（A） Security （B） Portability （C） integrity （D） concurrency control

7、 Database （B） It refers to the correctness and compatibility of data .

（A） Security （B） integrity （C） concurrency control （D） Data recovery

8、 Database （B） It is to ensure that the modification of the database by authorized users will not affect the consistency of data .

（A） Security （B） integrity （C） concurrency control （D） Data recovery

9、 Database system , Physical independence refers to （）

（A） The independence of database and database management system
（B） Application and DBMS Are independent of each other
（C） The physical mode of the application and the database stored on disk are independent
（D） The logical structure of the data in the application and database are independent of each other

10、 The characteristics of database system are （A）、 Data independence 、 Low data redundancy 、 Avoid data inconsistency 、 Provide data protection function .

（A） Data sharing （B） data storage （C） Data applications （D） Data protection

11、 The database management system realizes data query 、 Insert 、 Delete 、 The database language of the update operation is （C）.

（A） Data definition language （B） Data management language （C） Data manipulation language （D） Data control language

12、 In the three-level schema structure of the database , What describes the global logical structure and characteristics of a database is （D）.

（A） External mode （B） Internal mode （C） Storage mode （D） Pattern

13、 Division of database three-level schema structure , It is conducive to ensuring the （A）.

（A） Data independence （B） Data security （C） Structural standardization （D） Operational feasibility

14、 Data sharing is the main feature of database , Data sharing here refers to （C）.

（A） Multiple programs in the same application share a data set
（B） Multiple users 、 Share data in the same language
（C） Multiple users share a data file
（D） Multiple applications 、 A variety of languages 、 Multiple users use data sets that cover each other

15、 database （DB）、 Database system （DBS） And database management system （DBMS） The relationship between （A）.

（A）DBS contain DB and DBMS （B）DBMS contain DB and DBS （C）DB contain DBS and DBMS
（D）DBS Namely DB, That is to say DBMS

16、 The symbolic record describing things is called （B）.

（A） Information （B） data （C） Record （D） Record set

17、（A） It is a layer of data management software between the user and the operating system .

（A） Database management system （B） Database system （C） database （D） Database application system

18、 To ensure the data independence of the database , Need modification （A）.

（A） Two mappings between three-level patterns （B） Patterns and inner patterns （C） Pattern and outer pattern （D） Three level mode

19、 Which of the following statements is not true ？（C）

（A） Database reduces data redundancy （B） The data in the database can be shared
（C） The database avoids the duplication of all data （D） The database has high data independence

20、 Ensure the physical independence of data , Need modification （B）.

（A） Pattern （B） Mapping between patterns and inner patterns （C） Mapping between schema and external schema （D） Internal mode

21、 Which of the following does not describe the characteristics of the database ？（C）

（A） Data is shared （B） Data integrity （C） High data redundancy （D） High data independence

22、 The description of the data view used by a single user is called （A）.

（A） External mode （B） Conceptual model （C） Internal mode （D） Storage mode

23、 Subscheme DDL Used to describe the （）.

（A） The overall logical structure of the database （B） Local logical structure of data
（C） The physical storage structure of the database （D） Conceptual structure of database