Install mysql5.5 and mysql8.0 under windows at the same time

One 、 install mysql8.0

What I installed first was mysql5.5, Such as ：MySQL5.5 Installation tutorial +SQLyog install _ Qiqi's blog -CSDN Blog _mysql5.5 Installation steps of

1. Download decompression

link ：https://pan.baidu.com/s/13T-J-7rQI8iCMN2wE2Pxtw 
Extraction code ：2022

2. Create a configuration

After downloading , It is recommended to unzip to a path without Chinese , Create... In the extracted directory my.ini The configuration file

# These are the basic configuration information
[client]
# Set up mysql Client default character set
default-character-set=utf8

[mysqld]
# Set up 3306 port , I 5.5 Version with 3306 了 , It works 3307
port = 3307
# Set up mysql Installation directory
basedir=D:\MySQL8.0\mysql-8.0.26-winx64
# Set up mysql Database data storage directory
datadir=D:\MySQL8.0\mysql-8.0.26-winx64\data
# Maximum connections allowed
max_connections=20
# The character set used by the server defaults to 8 Bit coded latin1 Character set
character-set-server=utf8
# The default storage engine that will be used when creating a new table
default-storage-engine=INNODB

3. initialization MySQL

Administrators CMD Enter the bin Catalog , Input  mysqld --defaults-file=D:\MySQL8.0\mysql-8.0.26-winx64\my.ini --initialize --console

4. install MySQL service

Input mysqld install MySQL2  service name Do not enter the service name , The default is mysql

5. Sign in MySQL

Start the service first

Log in to the specified port , because 3306 By 5.7 The version uses mysql -uroot -p -P3307

Change Password , What I just generated is a temporary password , Have to change .

Input ALTER USER "root"@"localhost" IDENTIFIED BY " New password ";

Now the installation is complete .

Two 、 Solve password forgetting

​​​​​​​ Method 1 ：

First step ： close Mysql service

First stop mysql service . It can be done by net stop mysql Or close... In the task manager .

With Administrator rights operation ：（ This is the first window ）

The second step ： skip Mysql Password authentication

Go to the command prompt （ Administrator login ） operation , Get into mysql Directory bin Under the folder ,mysql8.0 The difference from other versions is that they cannot be used directly mysqld --skip-grant-tables To skip password login . Here we use  mysqld -console --skip-grant-tables --shared-memory  To skip permission verification .

No feedback after input execution , Open a new administrator window and re execute .（ This is the second window ）

After entering the catalog , Make sure you're closed Mysql Service for ：net stop mysql

close Mysql After the service , Continue to D:\mysql-8.0.19-winx64\bin Operating under the directory ：
Input

mysqld --console --skip-grant-tables --shared-memory 

After entering this line of code , As shown below , We have successfully skipped Mysql Login with your password ：

The third step ： Enter without password Mysql

After the above steps , Open another administrator mode cmd.exe （ This is the third window ）

Get into mysql Under the bin After the directory , Direct login mysql

No need to pass net start mysql open mysql service

Enter the following code on the command line

d:
cd D:\mysql-8.0.19-winx64\bin( Enter the installation directory on your computer here )
mysql -u root -p

Pictured ：

A message appears asking you to enter your password , Directly enter , You can successfully connect Mysql.

Step four ： Set the login password to blank

Enter the code , Set password to empty （ You cannot change the password directly at this time , Must be set to null first , Otherwise, an error will be reported ）
Input ：

use mysql; ( Use mysql Data sheet )
update user set authentication_string='' where user='root';（ Leave the password blank ）
quit; ( And then quit Mysql)

Operation as shown in figure ：

Step five ： Change your login password

There are two parts here

1. Close the first two cmd window ( Be sure to close ！);

2. Enter the code in the third window ;

net stop mysql( close mysql service , Although it will show that the service is not enabled , But just in case )
net start mysql( And on again mysql service )

( Don't bother here , If the last one mysql The service is not closed , We still log in without password )

Operation as shown in figure ：

Then the input ：

cd D:\mysql-8.0.19-winx64\bin  ( Enter the installation directory on your computer here )
mysql -u root -p
( Enter password... Will be displayed here , Just go straight back , Step 4 we have left him empty )
ALTER USER 'root'@'localhost' IDENTIFIED BY 'root';（ Change password ）

Pictured ：

The last step ： Verify that the password was modified successfully

Input ：

quit（ sign out mysql）
mysql -u root -p 
( Enter the new password , Log in again )

Icon ：

success ！

Method 2 ：

modify my.in/my.cnf The configuration file

　　　　 Get into mysql The installation directory

　　　　 edit my.ini

　　　　 stay [mysqld] Add below skip-grant-tables, Save it .

　　 Open the command line as an administrator

　　① restart mysql：

　　　　1、net stop mysql 2、net start mysql

　　② Get into mysql, Sign in
　　　　mysql -u root -p
　　　　 No password required , Directly enter （ appear Enter Password It's the same. Go straight back , You can login successfully ）

　　③ Input use mysql, modify root Password ：
　　　　update user set authentication_string=password(' New password ') where user='root';
　　　　flush privileges;

　　④ sign out ：

　　　　quit;

　　⑤ Restart again mysql：

　　　　1、net stop mysql 2、net start mysql

　　⑥ Whether the test is successful is whether the login is successful .
　　　　mysql -u root -p

　　　　Enter Password>' New password '

3、 ... and 、 uninstall

1. Out of Service

Administrators CMD, Input net stop mysql, I opened two services , therefore net stop mysql2

Select the version you want to delete OK 了

2. Uninstall service

I choose to delete the second

3. Delete installation files

Installation directory and data directory , All deleted .

4. Delete registry information

Registry path

• HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\
• HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Eventlog\Application\