1. Multiple choice questions
1. In the following descriptions, the ones that do not belong to the characteristics of the database system are ().
A. High data independence B. High data redundancy C. Good data sharing D. Good data consistency
2. In the database system, what describes the overall logical structure of all data is ().
A. External mode B. Conceptual mode C. Internal mode D. Storage mode
3. In the three-level schema structure of the database system, the user view belongs to ().
A. External mode B. Mode C. Internal mode D. Physical mode
4. In the database, the physical independence of data refers to ().
A. The user's application is independent of the data stored in the database on disk
B. The logical structure of the application and the data in the database are independent of each other
C. Mutual independence of database and database management system
D. Mutual independence of user program and DBMS
5. The main function of introducing two-level images between the three-level database modes is ().
A. Improve the independence of data and programs B. Improve the security of data and programs
C. Maintain the consistency of data and programs D. Improve the portability of data and programs
6. In the database system, it is ( ) that provides physical independence between data and applications.
A. External schema/logical schema image B. Logical schema/internal schema image
C. External schema/internal schema image D. Sub-mode/logical schema image
7. Among the following data models, the model that uses a two-dimensional table structure to represent the relationship between entities is ().
A. Relational model B. Network model C. Network model D. Hierarchical model
8. The core of the database system ().
A. Database B. Database Management System C. Data Model D. Data Storage
9. The most commonly used representation method of the conceptual model is ().
AE-R approach B. Data approach C. Distributed approach D. Object-oriented approach
2. Short answer
1. Understand data, information, data management, data processing.
1. Information is the abstract reflection of things by the human brain.
2. Data is a symbol used to record information and a form of expression of information.
3. Data processing is the process of converting data into information.
4. Data management is the core of data processing, which refers to defining, classifying, adding, deleting, modifying and checking data.
2. Understand database, database management system, database management.
1. A database is a warehouse for processing data.
2. A database management system is software that manages a database.
3. Database management is to define data, add, delete, modify, check, and constrain.
3. Compared with manual management and file system, what are the advantages of database?
1. The cost of manual management is high, the error tolerance rate is low, and it is easy to make mistakes.
2. The data redundancy of the file system is high, and the modification cost is high.
3. The database has low redundancy, good consistency, high independence and good sharing.
4. Understand the meaning of the three-level schema of the database and the two-level image.
1. External mode: The tables in the database that the user sees, the data contained in these tables and the relationship between the data are related to the specific needs of an application or user.
2. Schema: Summarizes all the data required by a database.
3. Internal mode: Describes the storage form of all data in the database on physical media.
5. Understand the data model and relational data model.
1. The data model is the core of the database and is an abstraction of data characteristics.
2. The relational data model is a collection of several relational schemas, and each relation can be regarded as a two-dimensional table.
6. Retrieval database application status, research hotspot technologies and development trends.
Research Hotspots
1. Non-volatile storage direction: It can be easily understood that the data stored in the memory will not be lost even if the power is turned off. There is no need to periodically refresh the slow disk or ssd operations such as log and snapshot, and the capacity of this new memory is still small. 4-16 times larger than general DRAM memory, but at the same time, this new memory speed is slower than DRAM. (Refer to Zhihu-Small Island cc)
2. Data security, differential privacy, query executor optimization, AI for DB/DB for AI.
7. Understand the following concepts
relation, tuple (record), attribute (field), field, primary key, candidate key, foreign key
The relationship can be seen as a two-dimensional table. The rows of the table are called tuples , which are used to identify an entity in the entity set; the columns of the table are called attributes, and the column names are the attribute names. The attribute names cannot be the same; the domain is to limit the attributes Range, specifying a type of value; candidate key can uniquely identify the attribute of a record, primary key is the only one selected from the candidate key; outer key is the primary key of the superior data table appearing in the subordinate data table.