本案例要求熟悉MySQL官方安装包的使用，快速构建一台数据库服务器：

安装MySQL-server、MySQl-client软件包
修改数据库用户root的密码
确认MySQL服务程序运行、root可控

1.2 方案

本课程将使用64位的RHEL 7操作系统，MySQL数据库的版本是5.7.17。

访问http://dev.mysql.com/downloads/mysql/，找到MySQL Community Server下载页面，平台选择“Red Hat Enterprise Linux 7/ Oracle Linux”，然后选择64位的bundle整合包下载

注意：下载MySQL软件时需要以Oracle网站账户登录，如果没有请根据页面提示先注册一个（免费）
1.3 步骤

实现此案例需要按照如下步骤进行。

步骤一：准备工作

1）停止mariadb服务

[root@localhost ~]# systemctl stop mariadb

2）删除/etc/my.cnf配置文件

此配置文件由RHEL自带的mariadb-libs库提供：

[root@localhost ~]# rm -rf /etc/my.cnf

3）删除数据

[root@localhost ~]# rm -rf /var/lib/mysql/*

4）卸载软件包（没有会显示未安装软件包）

[root@localhost ~]# rpm -e --nodeps mariadb-server mariadb `
警告：/var/log/mariadb/mariadb.log 已另存为/var/log/mariadb/mariadb.log.rpmsave

步骤二：安装软件包

1）安装mysql时可能会缺少某些依赖包，需提前单独安装

[root@localhost ~]# yum -y install perl-Data-Dumper perl-JSON perl-Time-HiRes

2）物理机传输解压包给虚拟机192.168.4.1

[root@room9pc01 ~]# cd 桌面            
[root@room9pc01 桌面]# scp mysql-5.7.17.tar 192.168.4.1:/root/  //给虚拟机传包
root@192.168.4.1‘s password:
mysql-5.7.17.tar     100%  543MB  95.6MB/s   00:05

3）虚拟机192.168.4.1解压mysql-5.7.17.tar 整合包

[root@localhost ~]# tar -xvf mysql-5.7.17.tar               //解压mysql整合包
./mysql-community-client-5.7.17-1.el7.x86_64.rpm
./mysql-community-common-5.7.17-1.el7.x86_64.rpm
./mysql-community-devel-5.7.17-1.el7.x86_64.rpm
./mysql-community-embedded-5.7.17-1.el7.x86_64.rpm
./mysql-community-embedded-compat-5.7.17-1.el7.x86_64.rpm
./mysql-community-embedded-devel-5.7.17-1.el7.x86_64.rpm
./mysql-community-libs-5.7.17-1.el7.x86_64.rpm
./mysql-community-libs-compat-5.7.17-1.el7.x86_64.rpm
./mysql-community-minimal-debuginfo-5.7.17-1.el7.x86_64.rpm
./mysql-community-server-5.7.17-1.el7.x86_64.rpm
./mysql-community-test-5.7.17-1.el7.x86_64.rpm

4)安装

[root@localhost ~]# yum -y install perl-JSON
[root@localhost ~]# rm -rf mysql-community-server-minimal-5.7.17-1.el7.x86_64.rpm
[root@localhost ~]# rpm -Uvh mysql-community-*.rpm
[root@localhost ~]# rpm -qa |grep -i mysql

步骤三：启动MySQL数据库服务并设置开机自启

[root@localhost ~]# systemctl start mysqld                  //启动mysql服务
[root@localhost ~]# systemctl enable mysqld                 //设置开机自启
[root@localhost ~]# systemctl status mysqld                 //查看mysql服务状态
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since 二 2018-08-28 10:03:24 CST; 8min ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
 Main PID: 4284 (mysqld)
   CGroup: /system.slice/mysqld.service
           └─4284 /usr/sbin/mysqld --daemonize --pid-file=/var/r...
8月 28 10:02:56 localhost.localdomain systemd[1]: Starting MySQ...
8月 28 10:03:24 localhost.localdomain systemd[1]: Started MySQL...
Hint: Some lines were ellipsized, use -l to show in full.

步骤四：连接MySQL服务器，修改密码

查看随机生成的root管理密码

[root@localhost ~]#grep ‘temporary password‘ /var/log/mysqld.log
2017-04-01T18:10:42.948679Z 1 [Note] A temporary password is generated for root@localhost: mtoa>Av<p6Yk        //随机生成的管理密码为mtoa>Av<p6Yk

2）使用客户端命令mysql连接到MySQL服务器

提示验证时，填入前一步获得的随机密码，验证成功后即可进入“mysql> ”环境：

[root@localhost ~]# mysql -u root -p‘mtoa>Av<p6Yk‘
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.7.17
Copyright (c) 2000, 2016, 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>                                     //登录成功后，进入SQL操作环境

用该密码登录到服务端后，必须马上修改密码，不然会报如下错误：

mysql> show databases;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

3）执行SET PASSWORD命令修改密码

这个其实与validate_password_policy的值有关，默认为1，所以刚开始设置的密码必须符合长度，且必须含有数字，小写或大写字母，特殊字符。如果我们不希望密码设置的那么复杂，需要修改两个全局参数：validate_password_policy与validate_password_length。validate_password_length默认值为8,最小值为4，如果你显性指定validate_password_length的值小于4，尽管不会报错，但validate_password_length的值将设为4。

可参考下列指令：

mysql>set global validate_password_policy=0;      //只验证长度
Query OK, 0 rows affected (0.00 sec)
mysql>set global validate_password_length=6；     //修改密码长度,默认值是8个字符 
Query OK, 0 rows affected (0.00 sec)
mysql> alter user user() identified by "123456";  //修改登陆密码
Query OK, 0 rows affected (0.00 sec)

上述操作的结果是——更改数据库用户root从本机访问时的密码，设为123456。

退出“mysql> ”环境，重新登录验证，必须采用新的密码才能登入：

mysql> exit                                  //退出 mysql> 环境
Bye
[root@localhost ~]# mysql -u root -p        //重新登录
Enter password:                              //输入新设置的密码
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 15
Server version: 5.7.17 MySQL Community Server (GPL)
Copyright (c) 2000, 2016, 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基础-构建MySql数据库：安装MySql-server、MySql-client