MySQL Learning summary, hope can see understand!

1. Database Overview
In short, a database is a warehouse where data is stored. To facilitate the storage and management of data, data is stored on disk in a specific pattern. Through the database management system, the data stored in the database can be effectively organized and managed. Today, there are many excellent databases such as Oracle, SQL Server, MySQL, and so on.

Detailed content:
How data is stored
The role of database in development
Database access Technology
Introduction to MySQL Database
Database generics
SQL language
Common Database Systems
If the Learning database

1.1 Theoretical basis of the database
A database can organize data according to specific rules. So, how the data is stored, what rules the database adheres to, and where the database is used, are some of the first things to know.

1.1.1 Data storage methods
Now the database is everywhere.
A web site needs to have a database to store data.
A school needs to use a database to store information about students and teachers.
A company needs to use a database to store employee information and company information.

To learn a database, you must first understand how the database stores the data.

Data development is divided into three phases:
1. Human Management Phase
2. File System phase
3. Database System phase
1.1.2 Database Generics

Database generics are the rules that a database should follow. Database generics are also called paradigms. The four most common paradigms currently used in relational databases are:
First Paradigm (1NF)
Second Paradigm (2NF)
Third Paradigm (3NF)
BCN Paradigm (BCNF)

When designing a database, the paradigm of minimum requirements that a database needs to meet is the first paradigm. The requirements table for the first paradigm cannot have duplicate fields, and each field can no longer be split. If there is a database even if the first paradigm is not satisfied, it can not be called a relational database. It is possible to create tables in this relational database only if the requirements of the first paradigm are met.

On the basis of satisfying the first paradigm, the database can be refined in one step. Refinement can make the database meet the requirements of the second paradigm. The third paradigm and the BCN paradigm can be obtained by thinning in turn.
The role of 1.1.3 database in development
Now most of the management systems and software need to use the database to store the data. The database has become an essential part of the development process. This section will give the reader a brief introduction to the role of the database in development.

In the process of software development, it is often necessary to use a database to store data. For example, a school's student management system needs a database to store student status information, test information, teachers ' information, curriculum information, and so on. For example, a bank's management system also needs a database to store information. Information such as bank accounts, deposits, deposits and withdrawals is stored in the database. When a user deposits money into his or her account, the management system updates the user's amount of money in the database.


1.2 Database system
1.2.1 Database system
Many readers think of databases as database systems, or DBS, for short. In fact, the scope of the database system is much larger than the database. Database system is not a simple database, but is composed of database, database management system and application development tools. Many times, database administrators and users can be part of a database system.

A database is where data is stored.
A database Management system, or DBMS, is the software used to define data, manage, and maintain data. It is an important part of the database system. Application systems are software that requires the use of a database. For example, student management system is an application system, this application system needs the database to manage its data. Application development tools are used to develop application systems.

1.2.2 SQL language
The full name of the SQL (Structured query Language) language is the Structured Query language. The database management system manages the data in the database through the SQL language.

The SQL language consists of three parts:
Data definition language (Language, referred to as DDL)
Data manipulation language (manipulation Language, referred to as DML)
Data Control Language (Language, referred to as DCL)
Data Query Language (Language, referred to as DQL)

MySQL Learning summary, hope can see understand!