MySQL introduction

Catalog

One 、MySQL brief introduction ：

Two 、MySQL User management of

  3、 ... and 、 Building database

Four 、 Four engines

One 、MySQL brief introduction ：

1. What is? MySQL？

Mysql Is a relational database management system （ Database is divided into relational database and non relational database , Relational databases have SqlServer、MySQL as well as Oracle wait , Non-relational databases do MongoDB、Cassandra as well as Redis wait ）, The Swedish MySQL AB Companies to develop , At present belongs to the Oracle Its products .MySQL characteristic ： Use a complete management system for unified management , Easy to query
 

2、Why（ Why use MySQL）

Because data is easy to lose in memory ,​ To save forever , Then use MySQL To save , And because the data is in the file , Not easy to operate .

 3、Where：( Where to use MySQl)

Where persistent data storage is needed .

 4、 The term ：
​          4.1DB：
​                     database （database）： Storing data “ Warehouse ”. It holds a series of organized data .
​         4.2DBMS：
​                     Database management system （Database Management System）. Database is through DBMS Create and manipulate containers
​         4.3SQL：
​                     Structured query language （Structure Query Language）： A language designed to communicate with a database
 

Two 、MySQL User management of

1、 Basic operation

1.1 Query all users

select * from USER

Running effect ：

1.

 1.2 A new user

create user jy

  1.3、 View the host address in the user , User name and password

-- Search the address of the user , User name and password 

select host,user,authentication_string from user

1.4、 Send new users jy The password of is set to 123456

-- Send new users jy The password of is set to 123456
ALTER user jy IDENTIFIED with mysql_native_password by '123456'

Running effect ： The password is encrypted

 2、 Set the permissions

First use the newly created user jy Establish a database connection , Then there will be one on the far left jy Little green whale

2.2 Set the permissions  

grant ALL on  Database name .* to [email protected]'%'    to user jy   give   All tables in the database   All permissions

2.3 Revoke authority ： Revoke all permissions of a user to use all tables in a database

General format ：REVOKE ALL on database_name.*FROM [email protected]'host' 

-- Undo to user jy database zjy All permissions of 

REVOKE ALL on zjy.* from [email protected]'%'

2.4 Query authority （show....for）

-- Query the user jy All permissions of 
show grants for 'jy' @'%'

Because the authority was revoked before , So there is only one login permission left

  3、 ... and 、 Building database

1、 Database building code

create database jy

2、 Set the code when building the database

create database if not EXISTS xz DEFAULT charset utf8 collate utf8_general _ci

Four 、 Four engines

  The four engines are ：InooDB、MyISAM、MEMORY、SHOW ENGINES. among InooDB It supports things , and MyISAM Do not support things , however MyISAM High query efficiency .
          Add ： Here it is InooDB、MyISAM Two data engines are commonly used ,
                    1.InooDB：
                                1、InnoDB The database engine has long been Mysql The direct product of flexible technology , This technology is mysql+api, In the use of mysql When , Almost every challenge you face
                                2、 From the isam and myisam Database engine , Support transaction processing and foreign keys .
                     2.MyISAM:
                                1、MyISAM yes MySQL Of ISAM Extended format .
                                2、MYISAM Fast read operations are emphasized , So it has the function of quick query .