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Database system concept
Machinery Industry Press
Sixth edition of the original book, translated edition
Chapter 1 Introduction
The database management system (Database management system) DBMS consists of a collection of interrelated data and a set of programs to access these data. This data collection is usually called a database
The main goal of DBMS is to provide a convenient and efficient way to access database information
1.3 Data View
One of the main purposes of a database system is to provide users with an abstract view of data (the system hides certain details about data storage and maintenance)
1.3.1 Data Abstraction
Physical layer: describes how the data is actually stored
Logical layer: describe what data is stored in the database and the relationship between these data (used by database administrators)
View layer: relatively simple, for users to use
1.3.2 Examples and patterns
The collection of information stored in the database at a specific time is called an instance of the database
The overall design of the database is called the schema of the database
1.3.3 Data Model
(1) Relational model (described by table)
(2) Entity-relation model (described by ER diagram later)
(3) Object-based data model
(4) Semi-structured data model
1.4 Database language
(1) DML (data manipulation language): data manipulation language
Including the language for deleting, modifying, and checking the database
(2) DDL (data definition language): data definition language
(3) DCL (data control language): data control function
Responsible for the security control function of the database
1.5 Relational database
1.5.1 Table
Each table has multiple columns, each column has a unique name
1.6 Database design
1.6.3 Entity-Relation Model
The entity-relationship model (ER) uses a set of basic objects called entities, and the connections between these objects
1.8 Transaction Management
(1) A transaction is a complete business logic unit and cannot be divided. For
example: bank account transfer, transfer 1000 yuan from account A to account B, you need to execute two update statements to update two tables
(2) the characteristics of the transaction: ACID (mentioned later)
to sum up
This chapter mainly introduces some basic concepts of database systems. There is no important content. Many concepts are still unfamiliar to newcomers who are just getting in touch with the database. However, as you deepen your learning, you will see more of these concepts later. Good understanding