Summary of database Principles and Applications Review questions, database principles questions

Summary of database Principles and Applications Review questions, database principles questions

 

Summary of database Principles and Applications Review questions

I. Single-choice questions (1 point for each question, 20 points in total)

1. In the three modes of the database, what actually stores data is () A. Internal Mode B. Mode C. External mode D. All three store data.

2. In three database modes ()

A. There is only one internal mode, and the external mode can have multiple

B. There is only one mode, while the internal mode and the external mode can have multiple

C. There is only one mode and one internal mode, while the external mode can have multiple

D. There is only one

3. Which of the following statements about the mode is false ()

A. Description of the global logical structure of the database B. Framework of the database

C. A set of modes D. data in the database

4. Which of the following statements is false ()

A. The database reduces data redundancy B. data in the database can be shared

C. The database avoids duplication of all data. D. The database has high data independence.

5. The company has multiple departments and multiple employees. Each employee can belong to only one department. A Department can have multiple employees. The contact type from the employee to the department is ()

A. many to many B. One to One C. Many to one D. One to many

6. Which of the following four items must be optimized ()

A. Relational Database B. Mesh database C. Hierarchical database D. Non-Relational Model

7. Which of the following operations cannot be performed on a view ()

A. Update View B. Query

C. define a new basic table in the view. D. define a new view in the view.

8. The three components of the relational data model do not include ()

A. integrity rules B. Data Structure C. Recovery D. Data Operations

9. Which of the following four items is not characteristic of relational databases ()

A. Small data redundancy B. High Data independence C. Good data sharing D. Multi-User Access

10. Possible problems caused by concurrent database operations include ()

A. Loss of updates B. Data independence will improve C. Use of illegal users D. Increase data redundancy

11. cannot be implemented in basic SQL language ()

A. Define View B. Define the base table C. query view and base table D. Concurrency Control

12. Which of the following are characteristic of the database system ()

A large storage capacity B fast processing speed C data sharing D easy to use

13. The E-R model that expresses the logical connection between entities is a database ()

A conceptual model B logical model C External Model D Physical Model

14. After performing the "projection" Operation on the relationship, the number of tuples and the number of tuples in the original relationship ()

A, B, less than meta-relationship C, greater than original relationship D, not greater than original relationship

15. Link "sales" includes attributes such as store name and product name. When querying the store names of the three commodities sold at the same time, the relational algebra operation should be ()

A select B Projection C Division D connection

16. In the "sales" table of the bookstore, attributes such as the book number, author number, publisher number, and price are defined. The main code is ()

A book no. B AUTHOR No. C Press No. D book no.

17. Which of the following statements about the SQL language is false ()

A. SQL language vocabulary is limited for easy learning.

B. the SQL language provides flexible and powerful query functions.

C. SQL is a non-procedural language.

D. Powerful SQL language to meet all application requirements

18. It indicates the concurrent processing of multiple transactions ()

A permanent B concurrency C seriality D isolation

19. In SQL language, the role of PRIMARY KEY is ()

A. Define the primary code B. Define the external code C. Define the reference table D. Determine the primary code type

20. database Triggers are used to define ()

A. Security Control B. integrity constraints C. Data Access scope D. deadlock Handling Method

2. Fill in blank questions (20 questions in this project, 1 point for each question, 20 points in total)

1. From the perspective of relationship Normalization Theory, there may be four problems in a relationship that only meets 1NF: large data redundancy, modification exceptions, insertion exceptions, and.

2. If all the attributes that satisfy the 1NF relationship are combined to form a keyword, the most satisfying paradigm of the relationship is3(Within the range of 1NF, 2NF, and 3NF ).

3. Data independence is divided----- Physical independence ----- and -- Logical independence ----, wherein ---- logical independence ---- are guaranteed by DBMS.

4. The language provided by DBMS for database operations is calledDatabase Operation Language, AbbreviatedDLL

5. There is a relationship between each property., --- One-to-one --, ----, one-to-many -------These three types of connections.

6. Assume that the link has the following functional dependencies: X1 → X2, X1 → X3, X1 → X4, the Link belongs2Paradigm because it existsFull dependency

7. relational operations in databases includeSelect,ConnectionAndProjectionThree.

8. Join Operations include two or moreLinkGenerateNew Link.

9. There is a student relationship. The keyword is student ID, and there is a course relationship. The keyword is the course number. There is also an elective relationship. The keyword is the combination of student ID and course number, the student ID and course number arePrimary and foreign keywords.

10. If the relationship between X and Y is, the dependency between X and Y isOne-to-one,X <à y.

11. In the same relational mode, if non-trivial functions depend on X → Y, Y → Z, and YX, then Z _____? ___ X.

12. Attributes contained in any candidate keyword are calledPrimary attributeThe attribute that is not included in any candidate keyword is calledNon-Primary attribute.

13. The first four stages of database application system design areRequirement Analysis,Conceptual Structure Analysis,And ___ Logical Structure Analysis ________. Physical Structure Analysis

14. In the E-R model, the entity is represented by the _____ rectangle box _____, the attribute is represented by the ___ elliptical _________ box, and the relationship between entities is represented by the _____ diamond _______ box.

15. A student can borrow multiple books at the same time. One book can only be borrowed by one student. The relationship between the student and the book is ___ one to many.

16. The tuples and attributes in the relationship correspond to ________ rows (Records) ________ and _ columns (fields) ___________ in the two tables respectively )___________.

17. The purpose of the system to block certain data in the databaseAvoid Concurrency Control.

18, in the E-R diagram, represented by a Rectangular BoxEntity, Represented in a diamond boxLink, Represented in an elliptical boxAttribute.

19. The unit of DBMS concurrency control isTransactions.

20. In the SQL language structure,Basic tableThere is a corresponding storage file, andViewThere is no corresponding storage file.

Iii. Short answer questions (5 points for each question, 10 points in total)

1. What functions does the database management system provide?

2. How to Ensure database security by defining views and access control? Use the SQL language as an example.

3. Department: includes the Department number, Department name, and office. Each department has multiple employees.

Employee: includes employee ID, name, gender, age, title, Major, and resume.

Resume: includes the start time, end time, work unit, and position.

Project: includes the Project ID, project name, project funding, project source, and owner.

Each employee can participate in multiple projects, and each project can be attended by multiple employees. Requirements:

1) draw an object Association diagram that expresses the problem.

2) write out the logical model of the relational database.

3) Draw a data structure diagram.

4) write the database and table definitions in SQL.

Reference answer

I. Single-choice questions (this is a total of 20 questions, each question is 1 point, a total of 20 points)

ACACC/ACCDA/DCADC/DDBAB

Iii. Short answer

1. What functions does the database management system provide?

A: The Database Management System (DBMS) is a data management software located between the operating system and the user. Its main functions include the following:

· Data definition functionDBMS provides a data description language (DDL) through which you can define data.

·Data manipulationDBMS also provides a data control language (DML) for basic database operations: Query, insert, delete, and modify.

·Database Operation ManagementThis is the core part of DBMS runtime, including development control, security check, integrity constraints check and execution, and database content maintenance.

·Database creation and maintenance functionsIt includes the input and conversion of initial database data, database dumping and recovery, Database Reorganization and performance monitoring and analysis.

3. How to Ensure database security by defining views and access control? Use the SQL language as an example.

The view can provide security protection for confidential data. With the view mechanism, you can define different views for different users when designing a database application system, so that confidential data does not appear in the user view that should not be seen, in this way, the view mechanism automatically provides security protection for confidential data. For example, if a Student table involves Student data of three departments, three views can be defined on it. Each view only contains the Student data of one department, only students in each department can query the student view of their own department.

For example, create a view for students in the information system.

Create view IS_Student

AS

SELECT Sno, Sname, Sage

FROM Student

WHERE Sdept = 'is ';

Database Security refers to protecting the database and preventing Data leaks and damages caused by illegal use. In the database system, the primary measure to ensure data security is access control, that is, to allow different users to perform operations on different data objects, and to control users to access only the data they have the right to access. The operation powers that different users have for different data are determined by the DBA and table creator (the owner of the table) according to the specific situation, the SQL language provides a means for DBAs and table owners to define and revoke such power.

For example, grant the Student Table query permission to u1.

Grant select on table Student TO U1;

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