[root@izwz91qnvovd6suufon1ccz ~]# wget http://dev.mysql.com/get/mysql57-community-release-el7-7.noarch.rpm

[root@izwz91qnvovd6suufon1ccz ~]# yum localinstall -y mysql57-community-release-el7-7.noarch.rpm

[root@izwz91qnvovd6suufon1ccz ~]# yum install -y mysql-community-server

[root@izwz91qnvovd6suufon1ccz ~]# systemctl start mysqld.service

service mysqld status

[root@izwz91qnvovd6suufon1ccz ~]# grep 'temporary password' /var/log/mysqld.log

2019-12-09T04:21:12.283622Z 1 [Note] A temporary password is generated for root@localhost: b;M%;tBXw5E8

[root@izwz91qnvovd6suufon1ccz ~]# mysql -u root -p

Enter password:  --使用上面的密码进入mysql

mysql> set password = password('yourpassword');
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> alter user 'root'@'localhost' password expire never;

Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

mysql> quit; --退出后再使用密码登陆

[root@izwz91qnvovd6suufon1ccz ~]# vim /etc/my.cnf

[mysqld]

#

lower_case_table_names=1  --在最后一行添加

[root@izwz91qnvovd6suufon1ccz ~]# firewall-cmd  --list-all

FirewallD is not running

1. 查看防火墙

firewall-cmd --list-all

2. 加入3306端口

firewall-cmd --permanent --add-port=3306/tcp  #添加完成后注意重启   
#删除端口  firewall-cmd --permanent --remove-port=8090/tcp  #删除完成后注意重启

3. 重启防火墙

service firewalld restart

4. 查看3306是否开放

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

-----------------------------------------------------------

--zone #作用域

--add-port=80/tcp #添加端口，格式为：端口/通讯协议

--permanent #永久生效，没有此参数重启后失效

firewall-cmd --permanent --zone=public --add-port=100-500/tcp #批量开启TCP端口

firewall-cmd --permanent --zone=public --add-port=100-500/udp

firewall-cmd --reload

-----------------------------------------------------------

5. 查看防火墙状态

systemctl status firewalld.service

6. 关闭防火墙

systemctl stop firewalld.service

7. 启动防火墙

systemctl start firewalld

8. 开机禁用防火墙

systemctl disable firewalld

9. 开机启用防火墙

systemctl enable firewalld

#创建用户的时候提示密码策略

Your password does not satisfy the current policy requirements

mysql> SHOW VARIABLES LIKE 'validate_password%'; #使用root查看密码策略

参数解释：

1).validate_password_dictionary_file 指定密码验证的文件路径;

2).validate_password_length  密码最小长度

3).validate_password_mixed_case_count  密码至少要包含的小写字母个数和大写字母个数;

4).validate_password_number_count  密码至少要包含的数字个数

5).validate_password_policy 密码强度检查等级，对应等级为：0/LOW、1/MEDIUM、2/STRONG,默认为1

注意：

0/LOW：只检查长度;

1/MEDIUM：检查长度、数字、大小写、特殊字符;

2/STRONG：检查长度、数字、大小写、特殊字符字典文件。

6).validate_password_special_char_count密码至少要包含的特殊字符数

mysql> set global  validate_password_mixed_case_count=0;

 #小写字母长度改下

mysql> create user myroot identified by 'ROOT@1234';

mysql> grant all privileges on *.* to 'myroot'@'%' IDENTIFIED BY 'ROOT@1234' WITH GRANT OPTION;

#设置开机启动

systemctl enable mysqld.service

#启动mysql

systemctl start mysqld

#停止

systemctl stop mysqld

#查看状态

systemctl status mysqld

查看字符集:

      方法一：show variables like '%character%';

      方法二：show variables like 'collation%';

设置字符集:

    /*建立连接使用的编码*/

    set character_set_connection=utf8;

    /*数据库的编码*/

    set character_set_database=utf8;

    /*结果集的编码*/

    set character_set_results=utf8;

    /*数据库服务器的编码*/

    set character_set_server=utf8;

    set character_set_system=utf8;

    set collation_connection=utf8;

    set collation_database=utf8;

    set collation_server=utf8;

设置完成后, 重启mysql字符集又失效了:

vim /etc/my.cnf文件:

    在[mysqld]里面添加 character-set-server=utf8

    重启mysql:

        service mysqld restart