Catalog

Chapter one ： Database Overview

1.0 What is a database

1.1 Database introduction

1.2 MySQL The advantages of

1.3 SQL The classification of languages

1.4MySQL8.0.22 install

---

Chapter one ： Database Overview

1.0 What is a database

From wikipedia ： database , Also known as data management system (DBMS), In short, it can be regarded as electronic Of File cabinet —— Storage Electronics file Premises , The user can be right file Data running in newly added 、 Intercept 、 to update 、 Delete Wait for the operation . So-called “ database ” Tied to Certain way Stored together 、 Can be given to multiple users share 、 As small as possible Redundancy 、 Data independent of the application aggregate . A database consists of multiple surface Space （Tablespace） constitute .

In a nutshell , A database is a warehouse for storing data , It's like you （DBA） To a warehouse （ database ）, Unlock first , Open door （DBMS）, Go into the warehouse and get （ Operational data ） What you need （ data ）; As shown in the figure below （ I drew it myself , If there are deficiencies , The comments indicate that ） Common database management system （DBMS） Yes ：Mysql,SQLserver,Oracle,DB2 etc. ;（ I'm here only for Mysql Make an introduction , But most database management systems have something in common ）

 

1.1 Database introduction

DB： database （database）： A for storing data ‘ Warehouse ’, Save a series of organized data .

DBMS( Database management system )： Database administrator （DBA） It's through DBMS To create and manage databases （DB） Of .

SQL： Structured query language , It's a language for communicating with databases （ By manipulating the sql Language to realize some functions ）

1.2 MySQL The advantages of

① Open source

    MySQL It's an open source database management system , Given the user can modify , Optimization and other permissions , This is also MySQL The power of , And very popular reasons .

② MySQL The cost is low

    MySQL There are community version and enterprise version , The Community Edition is completely free , And the enterprise edition is charged , But relative to Oracle、DB2 The charges are still relatively advantageous .

③ Cross platform

      To put it simply MySQL Can run on different operating systems , such as MySQL It can be used in office windows Up operation , It can also be used in the operating system commonly used by the server Unix Up operation .

④ Lightweight

MySQL The core program is fully multithreaded , These threads are lightweight processes , It is flexible to provide services for users at the same time , It doesn't take up too many resources . therefore MySQL Can be faster 、 Efficient data processing .

1.3 SQL The classification of languages

1、DML（Data Manipulation Language): Data manipulation statement , For adding Add 、 Delete 、 modify 、 Query database records , And check data integrity

      DML Used to query and modify data records , Includes the following SQL sentence ：

#"#" Indicates a single line comment ,/**/ For multiline comments 
#INSERT： Add data to the database 
#UPDATE： Modify the data in the database 
#DELETE： Delete data from database 
#SELECT： choice （ Inquire about ） data 

2、DDL（Data Definition Language): Data definition statement , For libraries and The creation of a table 、 modify 、 Delete .

      DDL Used to define the structure of the database , Such as creating 、 Modify or delete Database objects , Includes the following SQL sentence ：

/*
CREATE TABLE： Create database tables 
ALTER TABLE： Change table structure 、 add to 、 Delete 、 Modify column length 
DROP TABLE： Delete table 
CREATE INDEX： Index on a table 
DROP INDEX： Delete index 
*/

3、DCL（Data Control Language): Data control statement , Used to define Access rights and security levels of users .

      DCL Used to control database access , Includes the following SQL sentence ：

/*
GRANT： Grant access to 
REVOKE： Revoke access 
COMMIT： Commit transaction 
ROLLBACK： Transaction fallback 
SAVEPOINT： Set the savepoint 
LOCK： Lock specific parts of the database 
*/

1.4MySQL8.0.22 install

1. Download it first MySQL Installation package （ The website links ：https://dev.mysql.com/downloads/mysql/）【 Cloud disk ：https://pan.baidu.com/s/16TEiyq7oWe29Rpow_WzzMA Extraction code : j6b1 】
2. The official download （ Website is 8.0.23 edition , The first installation free version is also a command-line version without visual graphics ）

3. After downloading, unzip it to the path specified by yourself （ My path is F:\mysql\mysql-8.0.22-winx64\mysql-8.0.22-winx64\bin）

  

4. Configure environment variables

My computer –> attribute –> senior –> environment variable —>Path —> edit       Add... To the system variable  mysql Install under directory bin Folder address

5. The configuration file

establish mysql The configuration file , stay mysql Installation directory , newly build my.ini file , edit my.ini file , Pay attention to changing the path to your own file path .

## The contents of the configuration file are as follows 
[mysql]
 
#  Set up mysql Client default character set 
default-character-set=utf8
 
[mysqld]
 
# Set up 3306 port 
port = 3306
 
#  Set up mysql Installation directory （ Pay attention to changing to your own path ）
basedir=F:\mysql\mysql-8.0.22-winx64\mysql-8.0.22-winx64
 
#  Set up mysql Database data storage directory （ Pay attention to changing to your own path ）
datadir=F:\mysql\mysql-8.0.22-winx64\mysql-8.0.22-winx64\data
 
#  Maximum connections allowed 
max_connections=200
 
#  The character set used by the server defaults to 8 Bit coded latin1 Character set 
character-set-server=utf8

#  Number of connection failures allowed .
max_connect_errors=10
 
#  The default storage engine that will be used when creating a new table 
default-storage-engine=INNODB

6. install MySQL service

Open the command line as Administrator , Get into MySQL Installation directory bin Under the table of contents

# Enter the installation position bin Under the table of contents 
PS C:\Windows\system32> cd F:\mysql\mysql-8.0.22-winx64\mysql-8.0.22-winx64\bin
PS F:\mysql\mysql-8.0.22-winx64\mysql-8.0.22-winx64\bin>

# Run the installation code   win10  Super administrators may need to add ./ perhaps .\

mysqld --install

# perhaps .\mysqld --install

My is a blue background , Because I've already installed it, I brought the online map （ The appearance of successful installation is shown in the black background ）

next , initialization MySQL service , When finished, it will generate data File if not , Just create a , Then do it again

mysqld --initialize-insecure --user=mysql

7. Sign in

Once the initialization is complete , Start... First MySQL service , Then use the command to log in to MySQL

# start-up MySQL service ( You cannot log in until the service is started )
net  start  MySQL

# stop it MySQL service 
net  stop  MySQL

# Sign in MySQL, Install on your own computer ip Use localhost, The port number can be omitted （ It's usually 3306）
mysql -h  host IP Address  -P  Port number 	-u user name 	-p # enter 
Enter Password: password                             # You can enter directly without entering the password 

# Reset password 
alter user 'root'@'localhost' identified by ' Enter your own password ';
Query OK, 0 rows affected (0.01 sec) # It means that the modification was successful  

# Example 
mysql -h localhost -uroot -p


# Other clients , for example ： Visualization tools Navicat etc. 

Today's MySQL Overview installation , It's over here , I hope I can help the little friends who love learning , If there are shortcomings, please point out in the comments or private chat .