Record: install MySQL on ubuntu18.04

step

1. explain ： System is Ubuntu18.04.6 LTS

2. install MySQL, Directly using the command line （ You can also use other methods to install , See the first item in the reference catalogue ）
First , Enter the command to ensure that your warehouse has been updated

sudo apt update

then , install MySQL5.7 Enter the following command

sudo apt install mysql-server -y

Then wait a few minutes and the installation will succeed .

problem

When I enter or even want to open MySQL But I can't open it , Show Access denied for user ‘root‘@‘localhost‘ (using password: YES), The authority is not enough , there yes That is to say, you entered the password when logging in , If you don't enter the password, it will show NO, Access is denied .
Summary questions ：
A scenario ： This problem usually occurs just after the installation mysql When
Reasons for appearance ： Due to the use of commands sudo apt install mysql When installing , There is no prompt for password , Then the password is not initialized , Use root User login fails naturally .

resolvent

I found that the installation is the default installation , We didn't change our account password , So now let's change the account and password
1. Use cat Command to view the default user name and password

sudo cat /etc/mysql/debian.cnf 

Show content ：

# Automatically generated for Debian scripts. DO NOT TOUCH!
[client]
host     = localhost
user     = debian-sys-maint
password = HwPMmIAFg1GNU0OH
socket   = /var/run/mysqld/mysqld.sock
[mysql_upgrade]
host     = localhost
user     = debian-sys-maint
password = HwPMmIAFg1GNU0OH
socket   = /var/run/mysqld/mysqld.sock

2. Log in with the account and password written above , For example, the account number above is debian-sys-maint, The password is HwPMmIAFg1GNU0OH

mysql -udebian-sys-maint -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
……
mysql>

In this way, the login is successful
3. Then we change the default account password , modify PLUGIN Set up （ The reason for this problem is this ）, The account and password set here are root, You can change the account and password you want

UPDATE mysql.user SET authentication_string=PASSWORD('root'), PLUGIN='mysql_native_password' WHERE USER='root';

4. We need to restart our MySQL, I can see , The first is to close , The second is to open , We have to enter our boot password

/etc/init.d/mysql stop
/etc/init.d/mysql start

So we can log in
5. Sign in MySQL, Enter the following command , Then input root The password can enter , Exit can enter exit command

mysql -uroot -p

appendix ： If the change is not successful , Then uninstall and reload directly , The unloading steps are given below , sometimes MySQL There will be many other problems , Then you can also choose to reinstall .
Unload command ：

sudo rm /var/lib/mysql/ -R
sudo rm /etc/mysql/ -R
sudo apt-get autoremove mysql* --purge
sudo apt-get remove apparmor

Installation command ：

sudo apt-get update
sudo apt-get install mysql-server

see MySQL edition

Directly enter the following command

mysql -V

perhaps

mysql --version

see MySQL The installation path

whereis mysql

Here's the picture ：

Start off MySQL

There are several ways to start MySQL, I only remember the simplest , use service To start and shut down MySQL, And restart, of course ,（ Other methods of startup, shutdown and restart will be given in the reference website ） Direct orders
Be careful ： My version is 5.7.37, Different versions have different commands
1. Start command , To start, enter the login password

service mysql start
service mysqld start (5.0 The version is mysqld)

Nothing has changed since startup , But we can enter by command MySQL

mysql -uroot -p

Then enter the password to , Pictured ：

2. Exit command （ Exit from the database is exit）

service mysql stop
service mysqld stop (5.0 The version is mysqld)

Pictured ：

3. Restart command

service mysql restart 
service mysqld restart (5.0 The version is mysqld)

Refer to the website

How the Ubuntu Linux Installation on MySQL
Mysql:ERROR 1698 (28000): Access denied for user ‘root’@‘localhost’
Linux see MySQL Version information for
Linux start-up / stop it / restart Mysql Database method

notes ： Thank these authors for their articles , There may be some mistakes in the article , Please point it out in the comments , Common progress