CentOs7安装MySQL5.7

5.7相较于5.6来说，坑很多 因此写教程记录一下，以后用得上

1.通过ssh连接服务器

2.安装Mysql

1. 运行以下命令更新YUM源。

rpm -Uvh  http://dev.mysql.com/get/mysql57-community-release-el7-9.noarch.rpm

2. 运行以下命令安装MySQL。(镜像可能会稍微有点久，多等一会)

yum -y install mysql-community-server

3. 运行以下命令查看MySQL版本号。

mysql -v

返回结果如下，表示MySQL安装成功。
mysql Ver 14.14 Distrib 5.7.28, for Linux (x86_64) using EditLine wrapper

3.配置MySQL

1. 运行以下命令启动MySQL服务。

systemctl start mysqld

2. 运行以下命令设置MySQL服务开机自启动。

systemctl enable mysqld

3. 运行以下命令查看/var/log/mysqld.log文件，获取并记录root用户的初始密码。(下一步重置root用户密码时，会使用该初始密码)

grep 'temporary password' /var/log/mysqld.log
2019-11-13T09:22:30.998148Z 1 [Note] A temporary password is generated for root@localhost: c(dwuSJQP0pq

4. 运行下列命令对MySQL进行安全性配置。

mysql_secure_installation

4.配置MySQL的安全性

1. 重置root用户的密码。

Enter password for user root: #输入上一步获取的root用户初始密码
The 'validate_password' plugin is installed on the server.
The subsequent steps will run with the existing configuration of the plugin.
Using existing password for root.
Estimated strength of the password: 100 
Change the password for root ? ((Press y|Y for Yes, any other key for No) : Y #是否更改root用户密码，输入Y
New password: #输入新密码，长度为8至30个字符，必须同时包含大小写英文字母、数字和特殊符号。特殊符号可以是()` ~!@#$%^&*-+=|{}[]:;‘<>,.?/
Re-enter new password: #再次输入新密码
Estimated strength of the password: 100 
Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) : Y

2. 输入Y删除匿名用户账号。

By default, a MySQL installation has an anonymous user, allowing anyone to log into MySQL without having to have a user account created for them. This is intended only for testing, and to make the installation go a bit smoother. You should remove them before moving into a production environment.
Remove anonymous users? (Press y|Y for Yes, any other key for No) : Y  #是否删除匿名用户，输入Y
Success.

3. 输入Y禁止root账号远程登录。

Disallow root login remotely? (Press y|Y for Yes, any other key for No) : Y #禁止root远程登录，输入Y
Success.

4. 输入Y删除test库以及对test库的访问权限。

Remove test database and access to it? (Press y|Y for Yes, any other key for No) : Y #是否删除test库和对它的访问权限，输入Y
- Dropping test database...
Success.

5. 输入Y重新加载授权表。

Reload privilege tables now? (Press y|Y for Yes, any other key for No) : Y #是否重新加载授权表，输入Y
Success.
All done!

5.远程访问MySQL数据库

1. 通过以下命令登录mysql

mysql -uroot -p

2. 依次运行以下命令创建远程登录MySQL的账号。示例账号为root、密码为root。

mysql> grant all on *.* to 'root'@'%'IDENTIFIED BY 'root'; #使用root替换dms，可设置为允许root账号远程登录。
mysql> flush privileges;

简单密码修改方式

1. 通过以下命令登录mysql

mysql -uroot -p

2. 通过以下命令修改mysql默认的密码安全性

mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.05 sec)
 
mysql> 
mysql> 
mysql> set global validate_password_mixed_case_count=0;
Query OK, 0 rows affected (0.00 sec)
 
mysql> set global validate_password_number_count=3;
Query OK, 0 rows affected (0.00 sec)
 
mysql> set global validate_password_special_char_count=0;
Query OK, 0 rows affected (0.00 sec)
 
mysql> set global validate_password_length=3;
Query OK, 0 rows affected (0.00 sec)
 
mysql> SHOW VARIABLES LIKE 'validate_password%';
+--------------------------------------+-------+
| Variable_name                        | Value |
+--------------------------------------+-------+
| validate_password_dictionary_file    |       |
| validate_password_length             | 3     |
| validate_password_mixed_case_count   | 0     |
| validate_password_number_count       | 3     |
| validate_password_policy             | LOW   |
| validate_password_special_char_count | 0     |
+--------------------------------------+-------+

3. 修改简单密码：

mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD('root');
Query OK, 0 rows affected, 1 warning (0.00 sec)