Simple understanding of MySQL database

MySQL Database simple understanding

Basic concepts of database

data (Data)

• A symbolic record of things
• Including digital , written words 、 graphics 、 Images 、 voice 、 Records, etc
• With “ Record ” Forms are stored in a unified format

surface

• Organize different records together
• Used to store specific data

database

• Set of tables , It's a warehouse for storing data
• A collection of interrelated data stored in a certain organization
• It's organized according to the data structure 、 Warehouse for storing and managing data

Database management system （DBMS)

• Is to achieve effective organization of database resources 、 System software for management and access
• Establishment and maintenance of database 、 Data definition function 、 Data manipulation function 、 Database operation and management functions 、 Communications functions

Database system

• It's a human computer system , By hardware 、OS、 database 、DBMS、 Application software and database users
• The user can go through DBMS Or the application operates the database

The development of database

First generation database

• since 20 century 60 s , The first generation database system came out
• It is a database system of hierarchical model and mesh model
• It provides strong support for unified management and data sharing

Second generation database

• 20 century 70 s , Second generation database —— Relational databases are beginning to appear
• 20 century 80 s ,IBM The company's relational database system DB2 available , Start to gradually replace the database of hierarchical and mesh model , Become the mainstream of the industry
• up to now , Relational database system still occupies the main position of database application

Third generation database

• since 20 century 80 s , New database systems adapted to different fields are emerging
• Object oriented database system , Practical 、 It has a wide range of adaptability
• 20 century 90 Late S , A variety of database systems support applications together — Some new elements have been added to mainstream database systems
  for example ,Oracle Supported by “ Relationship ( object ” database model

The second generation database relational database stores rows in the form of tables – Column
Third generation database non relational data e file , picture , Key value pair , label , Sequence, etc
Document database , Index type , The time series

Introduction to mainstream database

SQLServer ( Microsoft products ）

• oriented Windows operating system
• Simple 、 Easy to use

Oracle ( Oracle products )

• For all mainstream platforms
• Security 、 perfect , The operation is complicated

DB2 (IBM The products of the company )

• For all mainstream platforms
• Sky type 、 Security 、 perfect

MySQL( Oracle buys )

• free 、 Open source 、 Small volume
  

Introduction to relational database

• A relational database system is a database system based on a relational model

• The data structure of relational model uses two-dimensional data table which is easy to understand

  • Each line is called a record , Information used to describe an object
  • Each column is called a field , Used to describe an attribute of an object

• The relational model can be simply “ Entity - Relationship ”(E-R) It is shown in the figure

• E-R The figure contains the entity （ Data objects )、 Three elements of relationship and attribute

• relational database ： Entity

  Also known as instances , Corresponding to... That can be distinguished from other objects in the real world “ event ” Or things "
  Such as bank customers 、 Bank accounts, etc

• relational database ： attribute

  A property of an entity , An entity can have multiple properties
  Such as “ Bank customers ” Each entity in the entity set has a name 、 address 、 Telephone, etc

• relational database ： contact
  The correspondence between entity sets is called connection , Also known as relationships, such as between bank customers and bank accounts “ savings ” The relationship between

• The collection of all entities and their relationships constitutes a relational database

The storage structure of relational database is two-dimensional tables in each two-dimensional table

• Each line is called a record , Information used to describe an object
• Each column is called a field , Used to describe an attribute of an object

Application of relational database

Relational database

• Oracle、Mysql
• SQLServer、Sybase
• Informix、access
• DB2、FoxPRO

Applications in life

• 12306 User information system
• Taobao account system
• Website user information system

Introduction to non relational database

• Non relational databases are also called NoSQL (Not Only SQL)
• Storing data is not based on a relational model , No fixed table format is required
• Advantages of non relational database
  • Database can be read and written with high concurrency
  • Efficient storage and access to massive data
  • Database has high scalability and high availability
• Common non relational databases
  • Redis
  • mongoDB
  • etc.

MySQL Database introduction

MySQL

• A popular open source relational database
• Oracle Our products
• comply with GPL agreement , It can be used and modified free of charge
• characteristic
  • Performance is remarkable 、 Stable service
  • Open source 、 No copyright restrictions 、 The cost is low
  • Multithreading 、 Multi user
  • be based on C/S（ client / The server ） framework
  • Safe and reliable

MySQL Installation method

See details before LNMP Medium MySQL install

mysql install