摘要：設置的密碼必須符合長度，且必須含有數字，小寫或大寫字母，特殊字符。可以看到只允許訪問更新用戶表強制刷新權限再次查看用戶表。查看端口監聽狀態，修改配置文件這里可以看到表示所有均可訪問。

1.準備

① 檢測系統是否自帶安裝 MySQL

rpm -qa | grep mysql

如有，類似mysql-libs-5.1.52-1.el6_0.1.x86_64那可以選擇進行卸載:

rpm -e mysql-libs-5.1.52-1.el6_0.1.x86_64　　// 普通刪除模式
rpm -e --nodeps mysql-libs-5.1.52-1.el6_0.1.x86_64　　// 強力刪除模式，如果使用上面命令刪除時，提示有依賴的其它文件，則用該命令可以對其進行強力刪除

② 檢查否存在 mariadb 數據庫，如有，卸載之

rpm -qa | grep mariadb

如有，類似

mariadb-libs-5.5.56-2.el7.x86_64

則卸載

rpm -e --nodeps mariadb-libs-5.5.56-2.el7.x86_64

2.安裝yum源

# 下載
[root@VM_0_6_centos ~]# wget https://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm

# 安裝mysql的yum源
[root@VM_0_6_centos ~]# sudo yum install mysql57-community-release-el7-11.noarch.rpm

檢查是否安裝成功

[root@VM_0_6_centos ~]# yum repolist enabled | grep "mysql.*-community.*"
mysql-connectors-community/x86_64    MySQL Connectors Community              131
mysql-tools-community/x86_64         MySQL Tools Community                   100
mysql57-community/x86_64             MySQL 5.7 Community Server              384

3.安裝MySQL

使用yum install命令安裝。注意：服務器在國外，下載會很慢，耐心等待即可。

[root@VM_0_6_centos ~]# sudo yum install -y mysql-community-server

# 安裝完成
Installed:
  mysql-community-server.x86_64 0:5.7.28-1.el7                                                                                          

Dependency Installed:
  mysql-community-client.x86_64 0:5.7.28-1.el7 mysql-community-common.x86_64 0:5.7.28-1.el7 mysql-community-libs.x86_64 0:5.7.28-1.el7
  numactl-libs.x86_64 0:2.0.12-3.el7_7.1      

Complete!

4.啟動MySQL服務

因為只有啟動了MySQL服務，才會產生/var/log/mysqld.log文件，初始root密碼在這個文件目錄下

啟動mysql服務（在CentOS7下，啟動和關閉服務的命令是systemctl start|stop）

# 現在我們來配置mysql的啟動，個人比較推薦使用服務的方式啟動（centos7特有）。
# 這樣就把mysqld這個服務添加到系統中了，我們可以用service進行啟動了
[root@VM_0_6_centos ~]# systemctl start mysqld.service

啟動，停止，重啟的命令如下

# 使用 service 啟動：service mysqld start
[root@VM_0_6_centos ~]# service mysqld stop
# 查看mysql狀態
[root@VM_0_6_centos ~]# systemctl status mysqld
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since Thu 2019-12-19 18:29:51 CST; 5s ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
  Process: 2514 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited status=0/SUCCESS)
  Process: 2497 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited status=0/SUCCESS)
 Main PID: 2517 (mysqld)
   CGroup: /system.slice/mysqld.service
           └─2517 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid

Dec 19 18:29:51 VM_0_6_centos systemd[1]: Starting MySQL Server...
Dec 19 18:29:51 VM_0_6_centos systemd[1]: Started MySQL Server.
# 使用 service 關閉：service mysqld stop
[root@VM_0_6_centos ~]# service mysqld stop
# 重啟
[root@VM_0_6_centos ~]# service mysqld restart

[root@VM_0_6_centos ~]# sudo systemctl start mysqld

查看mysql服務的啟動狀態

[root@VM_0_6_centos ~]# systemctl status mysqld

# 如下圖顯示則表示已經開啟
[root@VM_0_6_centos ~]# systemctl status mysqld
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since Thu 2019-12-19 17:29:42 CST; 25s ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
  Process: 26171 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited status=0/SUCCESS)
  Process: 26108 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited status=0/SUCCESS)
 Main PID: 26174 (mysqld)
   CGroup: /system.slice/mysqld.service

5.查看mysql的初始密碼

# S&3ytX**5rA8為默認密碼，修改之
[root@VM_0_6_centos ~]# sudo cat /var/log/mysqld.log | grep password
2019-12-19T09:29:37.272653Z 1 [Note] A temporary password is generated for root@localhost: S&3ytX**5rA8

6. 登錄mysql，修改密碼

# 登錄mysql
[root@VM_0_6_centos ~]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or g.
Your MySQL connection id is 3
Server version: 5.7.28

Copyright (c) 2000 2019 Oracle and/or its affiliates. All rights reserved.

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> 

# 設置密碼。設置的密碼必須符合長度，且必須含有數字，小寫或大寫字母，特殊字符。
mysql> set password=password("Zzj&zzj234812");
Query OK 0 rows affected 1 warning (0.00 sec)

mysql> 

# 刷新權限
mysql> flush privileges;
Query OK 0 rows affected (0.00 sec)

mysql> 

7.開啟遠程訪問

• 進入數據庫：mysql -u root -p
• 切換到 mysql庫：use mysql;
• 查看用戶表select hostuser from user;看到當前host是localhost只允許本地訪問。

# 可以看到只允許localhost訪問
mysql> select hostuser from user;
+-----------+---------------+
| host      | user          |
+-----------+---------------+
| localhost | mysql.session |
| localhost | mysql.sys     |
| localhost | root          |
+-----------+---------------+
3 rows in set (0.00 sec)

mysql> 

• 更新user用戶表

  
  mysql> update user set `host` = %  where `user` = root  LIMIT 1;
  Query OK 1 row affected (0.00 sec)
  Rows matched: 1  Changed: 1  Warnings: 0
  
  mysql> ^C

• 強制刷新權限

  mysql> flush privileges;

• 再次查看用戶表。

# root用戶的host變成%，即允許所有的ip遠程訪問，如果需要指定具體的ip，就填具體的ip即可。
mysql> select hostuser from user;
+-----------+---------------+
| host      | user          |
+-----------+---------------+
| %         | root          |
| localhost | mysql.session |
| localhost | mysql.sys     |
+-----------+---------------+
3 rows in set (0.00 sec)

mysql> 

• 查看端口監聽狀態netstat -an|grep 3306，修改mysql配置文件my.cnf

# 這里可以看到 0 0.0.0.0:3306 表示所有IP均可訪問。
# 如果顯示為 127.0.0.1:3306 說明只允許本地訪問，需要修改配置文件。
mysql> exit
Bye
[root@VM_0_6_centos ~]# netstat -an|grep 3306
tcp6       0      0 :::3306                 :::*                    LISTEN     
[root@VM_0_6_centos ~]# 

• 修改my.cnf。

注釋掉bind-address 127.0.0.1屬性。重啟mysql服務service mysql restart再次使用命令netstat -an|grep 3306查看端口監聽狀態:

[root@VM_0_6_centos ~]# netstat -an|grep 3306
tcp6       0      0 :::3306                 :::*                    LISTEN     
[root@VM_0_6_centos ~]# 

最后，服務器開放3306端口