Excerpt from database Book Review

Chapter 1 Introduction

Data: the basic object stored in the database

DB database: a collection of large amounts of data that has been stored in computers for a long time and can be shared. Function: 

 1. Data Definition (DDL)

2. Data organization, storage and management

3. data manipulation (DML)

4. Database Transaction Management and Operation Management

5. database creation and maintenance functions

6. Other functions: it is a layer of data management software (large and complex software systems) between users and operating systems)

 

DBS Database System: generally composed of databases, database management systems, application systems, and Database Administrators

Data Management: it refers to the classification, organization, encoding, storage, retrieval and maintenance of data. It is the central issue of data processing.

Data Processing: refers to the sum of a series of activities that collect, store, process, and disseminate various data.

Manual management stage: no storage or applicationProgramManage data, not share, not independent

File System stage: long-term storage, file system management data, poor sharing, large redundancy, and poor independence

Database System stage:

1. Data structuring

2. High data sharing, low redundancy, and easy expansion

3. High Data independence

4. Data is centrally managed and controlled by DBMS

 

The emergence of database systems has moved the new system from processing data programs to a new stage centered around shared databases.

Model: simulates and abstracts the features of an object in the real world.

Data Model: Abstraction of real-world data features (that is, data models are used to describe data, organize data, and operate on data)

Is the core and foundation of the database system.

Elements:

1. Data Structure

2. Data Operations

3. Constraints on Data Integrity

 

Common logical data models:

1. Hierarchical Model Data Structure:

1. There is only one node with no parent node. This node is called the root node.

2. Other nodes except the root node have only one parent node. It is suitable for handling one-to-many entity contact integrity constraints: When deleting a parent node, you must delete the child.

2. mesh model data structure:

1. allow more than one node to have no parent

2. One node can have more than one parent node. It is suitable for multiple-to-many entity contact integrity constraints: unique code, one-to-multiple parent-child, family-level constraints

3. Relational Model Data Structure: relational operations: Query, insert, delete, and update data

 

Integrity constraints: entity integrity, reference integrity, and user-defined integrity

 

Object-Oriented model object relational model classification:

First, conceptual model: modeling data and information from the user's point of view, mainly used for Database Design

Class II, logical model and Physical Model

 

Internal system structure of the database system: From the Perspective of the database management system, the database system usually adopts a three-level structure

 

External architecture of the database system: From the Perspective of the database end user, the structure of the database system is divided into single-user structure, master-slave structure, distributed structure, customer/Server, Browser/Application Server/Database Server multi-layer structure, etc.

 

Level 3 mode:

1. External mode: the logical structure and feature description of local data used by database users. It is the data view and mode subset of database users and multiple external modes of a database, one application and one external mode

2. Mode: the logical structure and feature description of all data in the database. It is the public data view of all users. One database mode is used.

3. Internal Mode: Describes the physical structure and storage mode of data. It is the internal representation of data in the database.

Secondary image:

1. External mode/mode (logical independence): the mode can change the external mode.

2. mode/internal mode (physical independence): the database storage structure change mode can remain unchanged

 

DBA Database Administrator:

1. determine the information content and structure in the database

2. Determine the storage structure and access policy of the database

3. Define data security requirements and integrity constraints

4. Monitor the use and operation of databases

5. database improvement and restructuring

 

Chapter 2 Relational Database

A relational database system supports relational models.

There are three types of relational data languages:

1. Relational algebra language

2. Relational algorithm language:

1. tuples relational algorithm language

2. Domain relational algorithm language

3. Relational algebra and relational Calculus

 

Database:

1. The link mode is a type, which is a description of the link.

2. The link is a value. There are three types:

1. Basic Relationship

2. query a table

3. Three types of integrity constraints of view chart relationships:

1. entity integrity: the primary attribute cannot be blank

2. Integrity of reference: the external code is null or one-to-one correspondence with the primary code

3. User-Defined integrity

 

<Relational algebra>

 

Chapter 3 relational database standard language SQL

<SQL statement>

 

Chapter IV database security

Computer Security: technical security, management security, policy and law

Database Security Technology: user identification and authentication, access control, view, and Password Storage

Encryption Method: replacement method and replacement method (combined with high security)

 

Chapter V database integrity

Database integrity index data correctness and compatibility

DBMS must provide: mechanisms to define integrity constraints, methods to provide integrity checks, and handling of defaults

 

 

Chapter 6 relationship data Theory

<Paradigm>

 

<Dependency>

 

Chapter 7 Database Design

<Database Design>

Chapter 8 Database Programming

 

Chapter 9 link query processing and Query Optimization

 

Chapter 10 database Restoration Technology

A transaction is a sequence of user-defined database operations.

Transaction Features: atomicity, consistency, isolation, and continuity

Transactions are the basic unit of recovery and concurrency control.

Possible database faults:

1. Internal transaction faults

2. system faults

3. Media faults

4. Computer Viruses

 

The recovery mechanism involves two key issues:

1. How to create redundant data (data dumping and logon log files)

2. How to Use the redundant data for real-time database recovery

 

Chapter 2 Concurrency Control