说明：

• 安装与卸载中，用户全部切换成为 root，一旦安装，普通用户就能使用。

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一、卸载内置环境

1、卸载不要的环境

[root@VM-8-5-centos ~]$ ps ajx | grep mariadb # 先检查是否有mariadb存在
13134 14844 14843 13134 pts/0 14843 S+ 1005 0:00 grep --color=auto mariadb
19010 19187 19010 19010 ? -1 Sl 27 16:55 /usr/libexec/mysqld --basedir=/usr
--datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --log-
error=/var/log/mariadb/mariadb.log --pid-file=/var/run/mariadb/mariadb.pid --
socket=/var/lib/mysql/mysql.sock
[root@VM-8-5-centos ~]$ systemctl stop mariadb.service # 停止mariadb服务
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to manage system services or units.
Authenticating as: root
Password:
==== AUTHENTICATION COMPLETE ===
[root@VM-8-5-centos ~]$ ps axj | grep mariadb # 停止完成
13134 14976 14975 13134 pts/0 14975 S+ 1005 0:00 grep --color=auto mariadb

mariadb 其实就是 mysql，只不过是 mysql 的另一种拉出来的开源分支，也可以正常使用，如果不想卸载也是可以的。

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2、检查系统安装包

[root@VM-8-5-centos ~]$ rpm -qa | grep mariadb
or
[root@VM-8-5-centos ~]$ rpm -qa | grep mysql
...
...
...

# 下面是打印出来的mysql的样例
[root@VM-8-5-centos ~]# rpm -qa | grep mysql
mysql-community-common-5.7.41-1.el7.x86_64
mysql-community-server-5.7.41-1.el7.x86_64
mysql57-community-release-el7-11.noarch
mysql-community-client-5.7.41-1.el7.x86_64
mysql-community-libs-5.7.41-1.el7.x86_64

---

3、卸载这些默认的安装包

#卸载显示出来的mariadb/mysql安装包
[root@VM-8-5-centos ~]$ sudo yum remove mariadb # 还是试着将上面的包都一个一个卸载吧


备份/etc/my.cnf,备份/var/lib/mysql数据

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4、获取 mysql 官方 yum 源

下载 MySQL yum包：

wget http://repo.mysql.com/mysql57-community-release-el7-10.noarch.rpm

#1. 获取mysql官方yum源 http://repo.mysql.com/
# 一定要看好下面的文字！如果后面自己安装不成功，就看看这个
# 注意：最好安装和自己系统一致的mysql版本，否则可能会存在软件兼容性问题
# 查看自己的系统版本
# [root@VM-8-5-centos ~]# cat /etc/redhat-release
# CentOS Linux release 7.8.2003(Core)
# 可以进入 http://repo.mysql.com/，找一下和自己版本一致的资源
# 下载到你的本地，然后上传到你的Linux服务器

---

二、 配置 MySQL yum 源

1、安装 mysql yum 源，对比前后 yum 源

安装 MySQL 源：rpm -Uvh mysql57-community-release-el7-10.noarch.rpm

安装前
[root@VM-8-5-centos MySQL]$ ls
mysql57-community-release-el7-10.noarch.rpm

查看你本地的yum源 [每个人的都不同，没有mysql相关的yum源]
[root@VM-8-5-centos MySQL]$ ls /etc/yum.repos.d/ -al
total 96
drwxr-xr-x. 2 root root 4096 Apr 12 11:04 .
drwxr-xr-x. 106 root root 12288 Apr 12 10:50 ..
-rw-r--r-- 1 root root 2523 Dec 26 19:31 Centos-Base.repo
-rw-r--r-- 1 root root 614 Nov 10 18:42 CentOS-Base.repo_bak
-rw-r--r-- 1 root root 2523 Jun 16 2018 CentOS-Base.repo.bak
-rw-r--r-- 1 root root 1309 Apr 8 2020 CentOS-CR.repo
-rw-r--r-- 1 root root 649 Apr 8 2020 CentOS-Debuginfo.repo
-rw-r--r-- 1 root root 230 Nov 10 18:42 CentOS-Epel.repo
-rw-r--r-- 1 root root 314 Apr 8 2020 CentOS-fasttrack.repo
-rw-r--r-- 1 root root 630 Apr 8 2020 CentOS-Media.repo
-rw-r--r-- 1 root root 998 Dec 11 2018 CentOS-SCLo-scl.repo
-rw-r--r-- 1 root root 971 Oct 29 2018 CentOS-SCLo-scl-rh.repo
-rw-r--r-- 1 root root 1331 Apr 8 2020 CentOS-Sources.repo
-rw-r--r-- 1 root root 7577 Apr 8 2020 CentOS-Vault.repo
-rw-r--r-- 1 root root 616 Apr 8 2020 CentOS-x86_64-kernel.repo
-rw-r--r-- 1 root root 1919 Apr 8 23:57 docker-ce.repo
-rw-r--r-- 1 root root 1050 Nov 1 04:33 epel.repo
-rw-r--r-- 1 root root 1149 Nov 1 04:33 epel-testing.repo
-rw-r--r-- 1 root root 173 Dec 9 16:08 google-chrome.repo
-rw-r--r-- 1 root root 1627 Apr 5 2017 mysql-community.repo #安装mysql yum源
-rw-r--r-- 1 root root 1663 Apr 5 2017 mysql-community-source.repo

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2、再看看能不能正常工作

[root@VM-8-5-centos MySQL]$ yum list |grep mysql
Repository epel is listed more than once in the configuration
mysql57-community-release.noarch el7-10 installed
akonadi-mysql.x86_64 1.9.2-4.el7 base
anope-mysql.x86_64 2.0.9-3.el7 epel
apr-util-mysql.x86_64 1.5.2-6.el7 base
calligra-kexi-driver-mysql.x86_64 2.9.10-2.el7 epel

collectd-mysql.x86_64 5.8.1-1.el7 epel

dmlite-plugins-mysql.x86_64 1.14.2-1.el7 epel

dovecot-mysql.x86_64 1:2.2.36-8.el7 base

 一开始的时候我们安装的 yum，在安装完之后是可以选择删除的，因为每次 yum 操作都会更新一次，耗费时间。

rpm -qa | grep mysql

yum -y remove mysql57-community-release-el7-10.noarch

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三、开始安装

1、安装 mysql 服务

安装 MySQL 服务端，需要等待一些时间：yum install -y mysql-community-server

[root@VM-8-5-centos MySQL]$ sudo yum install -y mysql-community-server
[sudo] password for root:
Loaded plugins: aliases, auto-update-debuginfo, fastestmirror, protectbase
Repository epel is listed more than once in the configuration
...
        Installing : mysql-community-common-5.7.33-1.el7.x86_64 #公共模块

        Installing : mysql-community-libs-5.7.33-1.el7.x86_64 #库
        Installing : mysql-community-client-5.7.33-1.el7.x86_64 #客户端
        Installing : mysql-community-server-5.7.33-1.el7.x86_64 #服务器
... #安装了服务和客户端

# 如果报错了，看第16步《常见问题》

---

2、查看配置文件和数据存储位置

[root@VM-8-5-centos MySQL]$ ls /etc/my.cnf
/etc/my.cnf
[root@VM-8-5-centos MySQL]$ sudo ls /var/lib/mysql
....

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3、启动服务 

启动 MySQL：systemctl start mysqld.service

[root@VM-8-5-centos MySQL]$ systemctl start mysqld.service
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to manage system services or units.
Authenticating as: root
Password:
==== AUTHENTICATION COMPLETE ===

---

4、查看启动服务

检查是否启动成功：systemctl status mysqld.service

[root@VM-8-5-centos MySQL]$ ps axj |grep mysqld
1 23183 23182 23182 ? -1 Sl 27 0:00 /usr/sbin/mysqld --daemonize --
pid-file=/var/run/mysqld/mysqld.pid
13134 23243 23242 13134 pts/0 23242 S+ 1005 0:00 grep --color=auto mysqld
[root@VM-8-5-centos MySQL]$ sudo ls -al /var/lib/mysql
total 122956
drwxr-x--x 5 mysql mysql 4096 Apr 12 11:23 .
drwxr-xr-x. 39 root root 4096 Apr 12 11:11 ..
-rw-r----- 1 mysql mysql 56 Apr 12 11:23 auto.cnf
-rw------- 1 mysql mysql 1680 Apr 12 11:23 ca-key.pem
-rw-r--r-- 1 mysql mysql 1112 Apr 12 11:23 ca.pem
-rw-r--r-- 1 mysql mysql 1112 Apr 12 11:23 client-cert.pem
-rw------- 1 mysql mysql 1676 Apr 12 11:23 client-key.pem
-rw-r----- 1 mysql mysql 436 Apr 12 11:23 ib_buffer_pool
-rw-r----- 1 mysql mysql 12582912 Apr 12 11:23 ibdata1
-rw-r----- 1 mysql mysql 50331648 Apr 12 11:23 ib_logfile0
-rw-r----- 1 mysql mysql 50331648 Apr 12 11:23 ib_logfile1
-rw-r----- 1 mysql mysql 12582912 Apr 12 11:23 ibtmp1
drwxr-x--- 2 mysql mysql 4096 Apr 12 11:23 mysql
srwxrwxrwx 1 mysql mysql 0 Apr 12 11:23 mysql.sock
-rw------- 1 mysql mysql 6 Apr 12 11:23 mysql.sock.lock
drwxr-x--- 2 mysql mysql 4096 Apr 12 11:23 performance_schema
-rw------- 1 mysql mysql 1680 Apr 12 11:23 private_key.pem
-rw-r--r-- 1 mysql mysql 452 Apr 12 11:23 public_key.pem
-rw-r--r-- 1 mysql mysql 1112 Apr 12 11:23 server-cert.pem
-rw------- 1 mysql mysql 1680 Apr 12 11:23 server-key.pem
drwxr-x--- 2 mysql mysql 12288 Apr 12 11:23 sys

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四、开始登陆

1、登陆方法一【不行就下一个】

获取临时密码，MySQL5.7 为 root 用户随机生成了一个密码：

grep 'temporary password' /var/log/mysqld.log

#获取临时root密码
[root@VM-8-5-centos MySQL]$ sudo grep 'temporary password' /var/log/mysqld.log
2021-04-12T03:23:46.153263Z 1 [Note] A temporary password is generated for root@localhost:
yLMalT:v+5l*

#使用临时密码登录
[root@VM-8-5-centos MySQL]$ mysql -uroot -p
Enter password:

#判断修改密码时候新密码是否符合当前的策略，不满足报错，不让修改，关闭它
#安全强度，默认为中，即1，要求必须包含 数字、符号、大小写字母，长度至少为8位
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.00 sec)

#密码最小长度
mysql> set global validate_password_length=1;
Query OK, 0 rows affected (0.00 sec)

#修改本地登录密码，暂不授权远程登录
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'yourpassword';
Query OK, 0 rows affected (0.00 sec)

mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)

# 如果你安装最新的mysql，没有所谓的临时密码，root默认没有密码

通过临时密码登录 MySQL，进行修改密码操作：mysql -uroot -p

使用临时密码登录后，不能进行其他的操作，否则会报错，这时候我们进行修改密码操作。

因为 MySQL 的密码规则需要很复杂，我们一般自己设置的不会设置成这样，所以我们全局修改一下：

mysql> set global validate_password_policy=0;

mysql> set global validate_password_length=1;

这时候我们就可以自己设置想要的密码了。

ALTER USER 'root'@'localhost' IDENTIFIED BY 'yourpassword';

---

2、登陆方法二【不行就下一个】

# 如果你安装的最新的mysql，没有所谓的临时密码，root默认没有密码
# 试着直接client登陆一下

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3、登陆方法三【应该行了吧】

[root@VM-8-5-centos MySQL]# vim /etc/my.cnf # 打开mysql配置文件

在[mysqld]最后一栏配置(不知道是什么，就放在配置文件最后) 加入：skip-grant-tables 选项，并保存退出

[root@VM-8-5-centos MySQL]# systemctl restart mysqld # 重启mysql服务

# 登陆成功
[root@VM-8-5-centos MySQL]# mysql -uroot
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.7.44 MySQL Community Server (GPL)

Copyright (c) 2000, 2023, 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.

mysql>

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五、设置配置文件

1、设置开机启动【可以不设】

先退出 mysql 命令行，然后输入以下命令：

#开启开机自启动
systemctl enable mysqld
systemctl daemon-reload

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2、配置 my.cnf

设置 MySQL 的字符集为 UTF-8，令其支持中文：

vim /etc/my.cnf

#配置一下my.conf,主要是数据库客户端和服务器的编码格式

[root@VM-8-5-centos MySQL]$ cat /etc/my.cnf
# 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

port=3306
character-set-server=utf8
default-storage-engine=innodb

datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

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

character-set-server=utf8
default-storage-engine=innodb

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
skip-grant-tables

# 配置完毕，重启mysql即可

重启一下 MySQL，令配置生效：

重启 mysql：service mysqld restart

or

停止 mysql：service mysqld stop

启动 mysql：service mysqld start

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3、常见问题：

mysql 已经配置了客户端服务器utf8编码，但是无法输入中文

确保您在终端命令行中可以输入中文
[root@VM-8-5-centos ~]$ env | grep LANG
LANG=en_US.utf8

 安装遇到秘钥过期的问题：
Failing package is: mysql-community-client-5.7.39-1.EL7.86_64
 GPG Keys are configured as: file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

解决方案:
rpm --import https://repo.mysql.com/RPM-GPG-KEY-mysql-2022