Introduction to database - a brief introduction to MySQL

Hello everyone , This time I bring you my new column ： database , The database is relatively not that difficult , As long as you practice hard 、 Memorize grammar , I believe that learning database well is not a problem , Bloggers will start from 0 analyse , Explain the knowledge points of database step by step , And will give many examples . most important of all , Bloggers will not use software , Use the most primitive way -> Command line to explain , The advantage of this explanation is to write sentence by sentence , It won't cause the problem that readers can't keep up with their ideas ！
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2.1 It's a " client - The server " The program of structure

MySQL This database , It's a “ client - The server ” The program of structure ～, So this “ client - The server ” It's the time of network communication , Both sides of the communication , Separate names .

• The party who initiated the request , It's called the client Data sent by the client to the server , be called “ request ”
• The party who passively accepts the request , It's called a server The data returned by the server to the client , be called “ Respond to “

You installed MySQL, It is equivalent to installing the client , The server is also installed , Between the client and the server is through “ The Internet ” To communicate ～

Then we configure the server and client to a host , But our computers are not connected to the Internet , Is it still possible to communicate ?

The answer is : Sure . If you are not connected to the network , We just can't access other hosts , But I can still visit myself , This is because the operating system performs some internal processing , Virtual out a special network card , be called " Loopback network card " .

So we use MySQL This is probably the case ～

Situation 1 ：

Situation two ：

Situation three ： A more typical case ～

Be careful ：MySQL The server is Database noumenon ,（ Save and manage data on the server side ）

2.2 MySQL Installation

Be careful ： We currently install MySQL, To use 5.x series （5.5,5.6,5.7… It doesn't matter ）, It must be a big version 5
The latest version is MySQL 8 series （ Don't suggest ）, For starters , Configuration is more complicated ～～

MySQL Installation tutorial for ( Oh, detailed , Bao Jiao Bao Association ~)_ Caribbean Haitao's blog -CSDN Blog

2.3 MySQL Chinese failure problem

MySQL Chinese failure problem _ Caribbean Haitao's blog -CSDN Blog

2.4 Related issues

2.4.1 Server program

Server programs generally do not need an interface , Just a quiet cat backstage , Help us do dirty work and hard work

Check the method ：

1. Search for -> service

   

2. find MySQL57, Normally , When you take your MySQL After successful installation , The status here is running , And it will start automatically every time you start it

   

3. We can also turn on and off the service in the command line

   net stop  The service name ;
   net start  The service name ;
   

   Other services can also use this statement

2.4.2 client

You can choose any one ( Recommended choice unicode)

After opening it, it looks like this

He will prompt us to enter the password , Enter the password we set before , It will be like this

To see this , Just explain , At present, our client , The database server has been connected

Next , Any request we make , In essence, the client sends a network request to the server , The server returned a specific response

！！！ Be careful ！！！

1. Don't make the password too complicated , Can't remember

2. Forget the password ： The easiest way -> reinstall （ Uninstall is also done by installing packages ,remove）
   You can also modify MySQL The configuration file for the server , Skip permission table login （ More trouble ）

3. Do you think it is unsafe to choose a password casually ？

   The answer is ： Can't ！ Very safe ！！！

   Our database has no valuable data , What kind of data is valuable data ？

   Computers used at work , Many of them belong to “ Trade secrets ”

2.5 Common database models

adopt "SQL" To manipulate the database , The database inside represents a MySQL An independent data set managed on the server ~

Take another chestnut ~

The educational administration system of the school , All have the function of selecting courses Scoring function View personal information function

Then we can analyze , We need several databases to store information with different functions .

Let's take the function of viewing personal information for example

In fact, that is database -> Data sheet -> That's ok -> Column

As long as it's a relational database , It stores data according to the above form

2.6 MySQL Preliminary operation of

1. Open with the command line MySQL

   Before , We can use it by opening the application in the menu bar MySQL, We can also connect to MySQL The server

    Log in locally （ Show the form of writing a password ）：mysql -uroot -p123456
   		
    Log in locally （ In the form of hidden passwords ）：mysql -uroot -p
   
   

   

   

2. Check the database version

   select version();
   

   

3. View currently used databases

   select database();
   

   

4. Import ready-made SQL file

   stay MySQL Input in source, Then drag the file to be imported

   source D:\study\MySQL\document\test.sql

   Be careful ： No Chinese in the path ！！！！

5. sign out MySQL:exit