MySQL 5.7 安装之 CentOS 7

环境准备

注意：这里使用 docker 模拟 centos 7 环境，前提已安装好 docker。

拉取镜像
$ docker pull centos:7

创建并运行容器
$ docker run --name centos -p 3307:3306 --privileged=true -d centos:7 /usr/sbin/init
模拟真实的 centos 环境不能用下面这条命令，否则无法使用 systemctl 命令启动服务
$ docker run --name centos -p 3307:3306 --privileged=true -d centos:7 /bin/bash

进入容器
$ docker exec -it 容器ID或名称 /bin/bash

安装 wget 包
$ yum -y install wget

更换国内 yum 源

Linux yum更换国内源（任选一个）
1 备份
$ cd /etc/yum.repos.d/
$ mv CentOS-Base.repo CentOS-Base.repo_bak

2 网易yum源：
$ wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo
$ yum clean all
$ yum makecache

3 阿里云yum源：
$ wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
$ yum clean all
$ yum makecache

4 epel源
$ yum -y install epel-release
$ yum clean all
$ yum makecache

安装 MySQL 5.7

下载Mysql源安装包
$ wget http://dev.mysql.com/get/mysql57-community-release-el7-8.noarch.rpm

yum安装mysql源
$ yum localinstall mysql57-community-release-el7-8.noarch.rpm -y

检查mysql源是否安装成功
$ yum repolist enabled | grep "mysql.*-community.*"

yum安装Mysql
$ yum install mysql-community-server -y

启动Mysql服务（如果 cmd 终端控制台不退出，貌似不影响，Ctrl+C 退出，继续执行后面的命令）
$ systemctl start mysqld

并添加开机启动
$ systemctl enable mysqld
$ systemctl daemon-reload

查看Mysql状态
$ systemctl status mysqld

查看默认的mysql密码。此时Mysql安装完成！接下来修改密码。
$ vi /var/log/mysqld.log

登录mysql
$ mysql -uroot -p 回车
密码： =>g6hj.Nx4e （上面查看的原始密码）

修改mysql的密码
第一次进入必须修改密码，建议先修改为默认密码加上几个字符，然后再更改密码规则策略，
才能修改为简单的密码，否则密码规则验证不通过，就不能修改密码成功。
mysql> set password for 'root'@'localhost'=password('g6hj.Nx4eAAA');

密码策略的修改仅限于开发环境下方便记忆
查看 mysql 初始的密码策略
mysql> SHOW VARIABLES LIKE 'validate_password%';
设置密码的验证强度等级为 LOW，长度最小为4
mysql> set global validate_password_policy=LOW;
mysql> set global validate_password_length=4;

修改 root 用户密码
mysql> set password for 'root'@'localhost'=password('root');

创建和删除用户（可省略）
mysql> CREATE USER 'username'@'%' IDENTIFIED BY 'password';
授权（开发环境，所有数据库所有权限）
mysql> GRANT ALL ON *.* TO 'username'@'%';
mysql> DROP USER 'username'@'%';

添加远程登陆的用户权限
mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'root' WITH GRANT OPTION;
mysql> FLUSH PRIVILEGES;

查看用户
mysql> use mysql;
mysql> select host,user,plugin from user;

退出mysql
mysql> exit;

修改mysql字符编码
$ vi /etc/my.cnf
添加
character_set_server=utf8mb4
init_connect='SET NAMES utf8mb4'

重启Mysql
$ systemctl stop mysqld
$ systemctl start mysqld

查看Mysql字符集（登录 mysql 后）
mysql> show variables like '%character%';

my.cnf 文件内容

# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html

[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

character_set_server=utf8mb4
init_connect='SET NAMES utf8mb4'

MySQL 卸载

$ rpm -qa|grep -i mysql
$ yum remove mysql-community-server -y
$ rpm -ev mysql-community-libs-5.7.33-1.el7.x86_64 --nodeps

删除文件
$ find / -name mysql
$ rm -rf /var/lib/mysql
$ rm -rf /etc/my.cnf