一般我们选择安装Centos的最小安装，然后我们在使用好多工具的时候就会报错！wget不会默认被安装。需要安装的看我之前的博客。

1、配置YUM源

下载mysql源安装包

[root@localhost~]#wget http://dev.mysql.com/get/mysql57-community-release-el7-8.noarch.rpm

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安装mysql源

1. 
   
2. [root@localhost~]# yum localinstall mysql57-community-release-el7-8.noarch.rpm
3. 提示【Is this ok [y/d/N]: y 输入y回车】
4. 检查MySQL源是否安装成功
5. [root@localhost ~]# yum repolist enabled | grep “mysql.-community.”

2、安装MySQL

[root@localhost ~]# yum install mysql-community-server

注意：安装过程中提示【Is this ok [y/d/N]: y 输入y回车】

出现以下表示安装成功：

1. 
   
2. Replaced:
3. mariadb-libs.x86_64 1:5.5.56-2.el7
5. Complete!

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3、启动MySQL服务

1. 
   
2. [root@localhost ~]# systemctl start mysqld
3. 查看MySQL的启动状态
4. [root@localhost ~]# systemctl status mysqld

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4.开机启动

1. 
   
2. [root@localhost ~]# systemctl enable mysqld
3. [root@localhost ~]# systemctl daemon-reload

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1. 查看mysql下root账号的默认密码
2. mysql5.7安装完成之后，在/var/log/mysqld.log文件中给root生成了一个默认密码。通过下面的方式找到root默认密码，然后登录mysql。
3. 命令：grep ‘temporary password’ /var/log/mysqld.log
4. [root@localhost /]# grep 'temporary password' /var/log/mysqld.log
5. 2017-10-17T08:07:03.797098Z 1 [Note] A temporary password is generated for root@localhost: 3prjY9ktM,eL
6. [root@localhost /]#
7. 默认的密码是：3prjY9ktM,eL

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1. 修改配置文件
2. 6.1. 默认配置文件路径
3. 配置文件：/etc/my.cnf
4. 日志文件：/var/log//var/log/mysqld.log
5. 服务启动脚本：/usr/lib/systemd/system/mysqld.service
6. socket文件：/var/run/mysqld/mysqld.pid
7. 6.2. 修改my.cnf文件
8. 6.2.1. 修改密码策略
9. mysql的密码策略分为三种：
10. 0或LOW：Length
11. 1或MEDIUM：Length; numeric, lowercase/uppercase, and special characters
12. 2或STRONG：Length; numeric, lowercase/uppercase, and special characters; dictionary file

在my.cnf文件中增加如下设置

如果不需要密码策略，禁用密码策略

validate_password = off

密码选择策略 0-LOW，1-MEDIUM，2-STRONG需要提供密码字典文件

validate_password_policy = 0

6.2.2. 修改字符编码为utf8

在[mysqld]下增加如下配置

character_set_server = utf8

init_connect = ‘SET NAMES utf8’

1. 
   
2. 例：
3. [root@localhost /]# cd /etc/
4. [root@localhost etc]# vi my.cnf
8. [client]
9. default-character-set=utf8
11. [mysqld]
12. #
13. # Remove leading # and set to the amount of RAM for the most important data
14. # cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
15. # innodb_buffer_pool_size = 128M
16. #
17. # Remove leading # to turn on a very important data integrity option: logging
18. # changes to the binary log between backups.
19. # log_bin
20. #
21. # Remove leading # to set options mainly useful for reporting servers.
22. # The server defaults are faster for transactions and fast SELECTs.
23. # Adjust sizes as needed, experiment to find the optimal values.
24. # join_buffer_size = 128M
25. # sort_buffer_size = 2M
26. # read_rnd_buffer_size = 2M
27. datadir=/var/lib/mysql
28. socket=/var/lib/mysql/mysql.sock
30. # Disabling symbolic-links is recommended to prevent assorted security risks
31. symbolic-links=0
33. log-error=/var/log/mysqld.log
34. pid-file=/var/run/mysqld/mysqld.pid
35. validate_password = off #设置禁用密码策略
37. character_set_server = utf8 #修改字符编码为utf8
38. init_connect = 'SET NAMES utf8'

6.2.3. 保存my.cnf并重启mysql服务是配置生效

命令：systemctl restart mysqld

登录mysql

命令：mysql -uroot -p

输入密码：默认为刚才查到的密码”3prjY9ktM,eL”

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2. [root@localhost etc]# mysql -uroot -p
3. Enter password:
4. Welcome to the MySQL monitor. Commands end with ; or \g.
5. Your MySQL connection id is 4
6. Server version: 5.7.20
8. Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
10. Oracle is a registered trademark of Oracle Corporation and/or its
11. affiliates. Other names may be trademarks of their respective
12. owners.
14. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
16. mysql>

修改密码

step 1: SET PASSWORD = PASSWORD('your new password');

step 2: ALTER USER 'root'@'localhost' PASSWORD EXPIRE NEVER;

step 3: flush privileges;

说明：

1. 如果之前没有设置密码策略，则密码12345678则不会通过验证，密码修改会失败

1. 密码修改不成功时则部分功能也无法使用，例如查看密码策略 show variables like ‘%password%’;
2. 查看密码策略
3. 命令：show variables like ‘%password%’;
4. 此处为 validate_password = off 设置后的结果
5. 查看字符编码
6. 命令：show variables like ‘%character%’;
7. 添加远程账户
8. mysql -u root -pvmwaremysql>use mysql;
9. mysql>update user set host = '%' where user ='root';
10. mysql>select host, user from user;
11. mysql>flush privileges;
12. 至此，可以远程连接并操作数据库啦！

7.退出Mysql命令

quit或者exit退出mysql

8.service iptables status可以查看到iptables服务的当前状态。

但是即使服务运行了,防火墙也不一定起作用,你还得看防火墙规则的设置 iptables -L

在此说一下关于启动和关闭防火墙的命令:

1) 重启后生效

开启： chkconfig iptables on

关闭： chkconfig iptables off

2) 即时生效，重启后失效

开启： service iptables start

关闭： service iptables stop

连接测试提示：2003 can’t connect to mysql server on ‘xxx.xxx.xxx.xxx’(10038)

解决办法：

centos查询端口是不是开放的

firewall-cmd –permanent –query-port=3306/tcp

添加对外开放端口

firewall-cmd –permanent –add-port=3306/tcp

重启防火墙

firewall-cmd –reload