安装mysql5.7

写卸载原来的mysql

[root@master mysql]# yum list installed | grep mysql
mysql-community-client-plugins.x86_64 8.0.36-1.el7                   @mysql80-community
mysql-community-icu-data-files.x86_64 8.0.36-1.el7                   @mysql80-community
mysql80-community-release.noarch      el7-3                          installed  
[root@master mysql]# yum -y remove mysql-community-client-plugins.x86_64 
开始下载

wget http://repo.mysql.com/mysql57-community-release-el7-8.noarch.rpm
rpm -ivh mysql57-community-release-el7-8.noarch.rpm
ls /etc/yum.repos.d/
yum install -y mysql-server

如果报错这个
Downloading packages:
warning: /var/cache/yum/x86_64/7/mysql57-community/packages/mysql-community-server-5.7.44-1.el7.x86_64.rpm: Header V4 RSA/SHA256 Signature, key ID 3a79bd29: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

The GPG keys listed for the "MySQL 5.7 Community Server" repository are already installed but they are not correct for this package.
Check that the correct key URLs are configured for this repository.

 Failing package is: mysql-community-server-5.7.44-1.el7.x86_64
 GPG Keys are configured as: file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

可以加入参数--nogpgcheck

yum -y install mysql-community-server --nogpgcheck

运行mysql

systemctl start mysqld
systemctl status  mysqld

查看初始密码

grep "password" /var/log/mysqld.log

进入mysql

mysql -u root -p

如果想设置比较简单的密码可以降低安全性

SET GLOBAL validate_password_policy=LOW;
SET GLOBAL validate_password_length=6;
ALTER USER USER() IDENTIFIED BY '123456';
ALTER USER 'root'@'localhost' PASSWORD EXPIRE NEVER;
flush privileges;