一、安装NGINX和PHP

# 先删除系统可能自带的PHP和nginx，用来面命令查找是否有安装
[root@localhost ~]# rpm -qa |grep php
[root@localhost ~]# rpm -qa |grep nginx
# 强制删除软件包，软件包全称就是上面通过rpm -qa 查询到的软件包全名
[root@localhost ~]# rpm -e --nodeps {软件包全称} 
# 安装yum的epel源，这里推荐用阿里云的镜像安装，包更全。
[root@localhost ~]# rpm -ivh https://mirrors.aliyun.com/epel/epel-release-latest-7.noarch.rpm
# 安装nginx
[root@localhost ~]# yum install -y nginx
# 安装php的源
[root@localhost ~]# rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm
# 安装php已经会用到扩展
[root@localhost ~]# yum install -y php70w-devel php70w-pear php70w-pecl php70w-gd php70w-opcache php70w-cli php70w-pdo php70w-process php70w-pecl-apcu php70w-mcrypt php70w-mysql php70w-fpm php70w-pecl-memcached php70w-common php70w-xml php70w-mbstring php70w-pecl-igbinary
 
# 检查是否安装成功

[root@localhost ~]# nginx -v
nginx version: nginx/1.16.1
[root@localhost ~]# php -v
PHP 7.0.33 (cli) (built: Dec  6 2018 22:30:44) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies
    with Zend OPcache v7.0.33, Copyright (c) 1999-2017, by Zend Technologies

二、安装MYSQL

#删除mariadb
#centos7 默认会安装mysql的另一个分支版本mariadb，在安装mysql前，需要将其删除

# 查出mariadb的rpm包
[root@localhost ~]# rpm -qa|grep mariadb
[root@localhost ~]# mariadb-libs-5.5.44-2.el7.centos.x86_64

# 忽略依赖关系，删除此包
[root@localhost ~]# rpm -e --nodeps mariadb-libs-5.5.44-2.el7.centos.x86_64
2. 添加官方yum源并安装mysql
# 下载安装此yum仓库
[root@localhost ~]# rpm -ivh https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm

# 安装完成后，此yum源仓库默认是安装mysql最新版8.0版本。
# 需要我们修改一下文件中的下列项，使其下载5.7版本，如果要安装别的版本，就打开对应版本，将别的版本关闭即可。
[root@localhost ~]# vim /etc/yum.repos.d/mysql-community.repo
----------------------------------------------------------------
# Enable to use MySQL 5.7
[mysql57-community]
name=MySQL 5.7 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/$basearch/
enabled=1    # 这里将0改为1，开启5.7版本
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

[mysql80-community]
name=MySQL 8.0 Community Server
baseurl=http://repo.mysql.com/yum/mysql-8.0-community/el/7/$basearch/
enabled=0    # 这里将1改为0，关闭8.0版本
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
----------------------------------------------------------------

# 修改完成后，安装mysql5.7
[root@localhost ~]# yum install -y mysql-community-server
安装完成后，配置文件为 /etc/my.cnf 根据实际情况进行配置。
3. 启动服务，开启远程访问
# 启动mysql服务
[root@localhost ~]# systemctl start mysqld

# 设为开启自启动
[root@localhost ~]# systemctl enable mysqld

# 第一次启动mysql后，会自动生成一个初始密码在日志文件中，默认的日志文件路径为：/var/log/mysqld.log
# 找出初始化密码
[root@localhost ~]# cat /var/log/mysqld.log |grep password
2019-06-18T12:12:04.161088Z 1 [Note] A temporary password is generated for root@localhost: 2%w)IDysCVZQ

# 这里密码就是上面输出的那段，使用此密码登录mysql
[root@localhost ~]# mysql -u root -p 
# 复制密码输出，进入mysql
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.7.26

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> 

# 修改密码，mysql5.7的默认密码强度很高，需要有大小写，符号和数字，长度大于6，缺一不可
mysql> alter user 'root'@'localhost' identified by 'your_password';
Query OK, 0 rows affected (0.00 sec)

# 如果你不像要这么复杂的密码，修改密码强度设定为最低，即只判断密码长度
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.00 sec)

# 开启远程访问
$ grant all privileges on *.* to 'root'@'%' identified by 'your_password';
Query OK, 0 rows affected, 1 warning (0.00 sec)

# 刷新权限生效
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)



# 到此就完成了mysql的最初设置了，现在就可以用账号密码，访问此mysql服务了
# 访问之前别忘了要打开数据库3306端口
$ firewall-cmd --add-port=3306/tcp --permanent
$ firewall-cmd --reload

修改密码

[root@localhost ~]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 8.0.24
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
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> 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)
mysql> alter user 'root'@'localhost' identified by '123456';
Query OK, 0 rows affected (0.01 sec)
mysql> exit
Bye

遇到的问题

mysql> set global validate_password_policy=0;
ERROR 1193 (HY000): Unknown system variable 'validate_password_policy'
mysql> set global validate_password_length=4
ERROR 1193 (HY000): Unknown system variable 'validate_password_length'

问题原因
// 适用于sql的老版本如mysql5.0
mysql> set global validate_password_policy=0;
mysql> set global validate_password_length=4
// 新版本如mysql8.0就不支持了
// 为啥呢，进入mysql命令后，输入下面命令就清清楚楚了！
mysql> SHOW VARIABLES LIKE 'validate_password%';
// 结果如下
+--------------------------------------+--------+
| Variable_name                        | Value  |
+--------------------------------------+--------+
| validate_password.check_user_name    | ON     |
| validate_password.dictionary_file    |        |
| validate_password.length             | 8      |
| validate_password.mixed_case_count   | 1      |
| validate_password.number_count       | 1      |
| validate_password.policy             | MEDIUM |
| validate_password.special_char_count | 1      |
+--------------------------------------+--------+
7 rows in set (0.01 sec)

实际解决
在Mysql中输入如下命令
mysql> set global validate_password.policy=0; // 调整设置密码策略
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password.length=1; //调整设置密码长度
Query OK, 0 rows affected (0.00 sec)
mysql> alter user 'root'@'localhost' identified by '123456';
Query OK, 0 rows affected (0.01 sec)

# 开启远程访问
$ grant all privileges on *.* to 'root'@'%' identified by 'your_password';
Query OK, 0 rows affected, 1 warning (0.00 sec)

# 刷新权限生效
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)