1.先查询是否安装MySQL
大多数centos 6 自带 MySQL5.1
命令：
rpm -qa|grep mysql
执行：
[root@lifan ~]# rpm -qa|grep mysql
mysql-libs-5.1.73-7.el6.i686
2.若有则卸载
rpm -e --nodeps mysql-libs
--nodeps 是消除依赖的意思
3.去官网复制yum下载链接用wget下载到服务器
https://dev.mysql.com/downloads/repo/yum/
命令：
wget https://dev.mysql.com/get/mysql80-community-release-el6-1.noarch.rpm
成功：
[root@lifan ~]# wget https://dev.mysql.com/get/mysql80-community-release-el6-1.noarch.rpm
--2018-12-10 06:40:42--
...
Length: 25800 (25K) [application/x-redhat-package-manager]
Saving to: “mysql80-community-release-el6-1.noarch.rpm”
2018-12-10 06:40:42 (95.8 MB/s) - “mysql80-community-release-el6-1.noarch.rpm” saved [25800/25800]
若没有wget
[root@lifan ~]# wget https://dev.mysql.com/get/mysql80-community-release-el6-1.noarch.rpm
-bash: wget: command not found
安装wget
yum -y install wget
4.安装
第一步：
rpm -ivh mysql80-community-release-el6-1.noarch.rpm
执行成功结果：
[root@lifan ~]# rpm -ivh mysql80-community-release-el6-1.noarch.rpm
warning: mysql80-community-release-el6-1.noarch.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Preparing... ########################################### [100%]
1:mysql80-community-relea########################################### [100%]
[root@lifan ~]#
第二步：
yum install mysql-server
执行后会跳出2次选择，输入y回车继续即可，如：
[root@lifan ~]# yum install mysql-server
Loaded plugins: fastestmirror
...
Install 5 Package(s)
Total download size: 452 M
Installed size: 1.7 G
Is this ok [y/N]: y
输入y继续安装：
...
Total 16 MB/s | 452 MB 00:28
warning: rpmts_HdrFromFdno: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
Importing GPG key 0x5072E1F5:
Userid : MySQL Release Engineering <mysql-build@oss.oracle.com>
Package: mysql80-community-release-el6-1.noarch (installed)
From : /etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
Is this ok [y/N]: y
最后出现如下指令，安装成功：
Installed:
mysql-community-server.i686 0:8.0.13-1.el6
Dependency Installed:
mysql-community-client.i686 0:8.0.13-1.el6 mysql-community-common.i686 0:8.0.13-1.el6 mysql-community-libs.i686 0:8.0.13-1.el6 numactl.i686 0:2.0.9-2.el6
Complete!
5.查询是否安装成功
[root@lifan ~]# mysqladmin -V
mysqladmin Ver 8.0.13 for Linux on i686 (MySQL Community Server - GPL)
6.开启MySqL
[root@lifan ~]# service mysqld start
Initializing MySQL database:
[ OK ]
Starting mysqld: [ OK ]
查看MySQL启动状态:
[root@lifan ~]# service mysqld status
mysqld (pid 3852) is running...
7.查看系统给root自动生成的密码
cat /var/log/mysqld.log
执行结果（密码在第二行最后）：
[root@lifan ~]# cat /var/log/mysqld.log
2018-12-10T12:19:20.303739Z 0 [System] [MY-013169] [Server] /usr/sbin/mysqld (mysqld 8.0.13) initializing of server in progress as process 3620
2018-12-10T12:19:24.878215Z 5 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: >J9tXQXwK3y=
2018-12-10T12:19:29.237165Z 0 [System] [MY-013170] [Server] /usr/sbin/mysqld (mysqld 8.0.13) initializing of server has completed
2018-12-10T12:19:32.011310Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.13) starting as process 3852
2018-12-10T12:19:33.144590Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.
2018-12-10T12:19:33.201007Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.13' socket: '/var/lib/mysql/mysql.sock' port: 3306 MySQL Community Server - GPL.
2018-12-10T12:19:33.272837Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Socket: '/var/run/mysqld/mysqlx.sock' bind-address: '::' port: 33060
8.命令行登录和修改密码
[root@lifan ~]# mysql -uroot -p
Enter password:
输入上一步骤查看的密码（输入时不显示任何字符）：
[root@lifan ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor.
...
mysql>
修改密码：
mySql5.7之后，必须修改密码后才能操作.
并且对密码要求严格，至少8位，包含大小写等，若想设置成123456，则要以下两条命令：
mysql> set global validate_password.policy=0;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password.length=1;
Query OK, 0 rows affected (0.00 sec)
设置密码：
mysql> alter user user() identified by '123456';
Query OK, 0 rows affected (0.09 sec)
9.远程登录（Navicat）
注意：需关闭防火墙或者开放3306端口
service iptables stop #暂时关闭
chkconfig iptables off #设置成开启不自启
==========
/sbin/iptables -I INPUT -p tcp --dport 3306 -j ACCEPT #开启3306端口
/etc/rc.d/init.d/iptables save #保存配置
/etc/rc.d/init.d/iptables restart #重启服务
远程登录会报如下错误：
首先查看用户表，发现登录主机是localhost，当然不能登录，把root用户的localhost设置为%，这样任意主机都可以连接。
mysql> use mysql;
Database changed
mysql> select user,host from user;
+------------------+-----------+
| user | host |
+------------------+-----------+
| mysql.infoschema | localhost |
| mysql.session | localhost |
| mysql.sys | localhost |
| root | localhost |
+------------------+-----------+
4 rows in set (0.00 sec)
mysql> update user set host = '%' where user ='root';
再刷新一下:
flush privileges;
这时该问题已解决，若报如下错误，则是版本加密方式的改变
登录后请依次执行如下命令：
use mysql;
ALTER USER 'root'@'%' IDENTIFIED BY '123456' PASSWORD EXPIRE NEVER; #更改加密方式
ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY '123456';#更新用户密码
FLUSH PRIVILEGES;#刷新权限
再次连接成功：
