Centos7 install MySQL 8 0

# View the installed on the current system mysql
[root@localhost ~]# rpm -qa | grep -i mysql
MySQL-test-5.6.49-1.el7.x86_64
MySQL-client-5.6.49-1.el7.x86_64
MySQL-embedded-5.6.49-1.el7.x86_64
MySQL-shared-5.6.49-1.el7.x86_64
MySQL-server-5.6.49-1.el7.x86_64
MySQL-devel-5.6.49-1.el7.x86_64
MySQL-shared-compat-5.6.49-1.el7.x86_64

#  Uninstall the installation package 
[root@localhost ~]# yum -y remove MySQL*
 Loaded plug-in ：fastestmirror
 Resolving dependencies 
-->  Checking transactions 
--->  software package  MySQL-client.x86_64.0.5.6.49-1.el7  Will be   Delete 
--->  software package  MySQL-devel.x86_64.0.5.6.49-1.el7  Will be   Delete 
--->  software package  MySQL-embedded.x86_64.0.5.6.49-1.el7  Will be   Delete 
--->  software package  MySQL-server.x86_64.0.5.6.49-1.el7  Will be   Delete 
--->  software package  MySQL-shared.x86_64.0.5.6.49-1.el7  Will be   Delete 
...............
 complete ！

# Delete the previous MySQL Folder 
[root@localhost teach_jmp]# rm -rf my*
[root@localhost /]# find / -name mysql
/etc/selinux/targeted/active/modules/100/mysql
/var/lib/mysql
/var/lib/mysql/mysql
[root@localhost /]# rm -rf /var/lib/mysql

#  Delete profile 
[root@localhost lib]# rm -rf /etc/my.cnf

# Delete default password 
[root@localhost lib]# rm -rf /root/.mysql_secret

# download msyq8.0 Official mirror image 
[root@localhost mysql]# wget -i -c http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rp m
--2022-04-18 13:43:07--  http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
............
2022-04-18 13:43:25 (131 KB/s) -  Saved  “mysql57-community-release-el7-10.noarch.rpm” [25548/25548])
........
Downloaded: 1 files, 25K in 0.2s (131 KB/s)

# install mysql8.0 --nogpgcheck Mandatory installation （ solve ：mysql-community-libs-compat-5.7.37-1.el7.x86_64.rpm  The public key for has not been installed ）
[root@localhost mysql]# yum install -y mysql-community-server --nogpgcheck
 Loaded plug-in ：fastestmirror
....... The process is omitted 
 complete ！

# start-up MySQLd
[root@localhost mysql]# systemctl start mysqld

# Check the default root password 
[root@localhost ~]# grep "A temporary password" /var/log/mysqld.log
2022-04-18T05:58:24.900384Z 6 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: Xl8aVOd99)<G

# Sign in root user 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 8.0.28

Copyright (c) 2000, 2022, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

# Set up root password , Report errors ： The password is not secure , Too simple 
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY '1234';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

# Change password policy , If an error is reported, you must first set a password that conforms to the default policy , To modify the password policy .
mysql> set global validate_password.length=4;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

# Set a complex password 
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'Qwer@1234';
Query OK, 0 rows affected (0.01 sec)

# The password length for modifying the password policy is 4
mysql> set global validate_password.length=4;
Query OK, 0 rows affected (0.00 sec)

# The complexity level is 0,
mysql> set global validate_password.policy=0;
Query OK, 0 rows affected (0.01 sec)

# Turn off whether to check whether the user name and password are the same 
mysql> set global validate_password.check_user_name=off;
Query OK, 0 rows affected (0.00 sec)

# Change Password 
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY '1234';
Query OK, 0 rows affected (0.00 sec)
mysql>