1、卸载系统自带的 mariadb-lib

[root@centos-linux ~]# rpm -qa|grep mariadb
mariadb-libs-5.5.44-2.el7.centos.x86_64
[root@centos-linux ~]# rpm -e mariadb-libs-5.5.44-2.el7.centos.x86_64 --nodeps

#### 2、下载 rpm 安装包

去官网找到最新的 rpm 集合包。现在最新的是 mysql-5.7.13-1.el7.x86_64.rpm-bundle.tar

复制其下载地址，在服务器下载 (或者本地下载了上传至服务器)。

[root@centos-linux ~]# wget http://dev.mysql.com/get/Downloads/MySQL-5.7/mysql-5.7.13-1.el7.x86_64.rpm-bundle.tar

然后解压

[root@centos-linux ~]# ls
mysql-5.7.13-1.el7.x86_64.rpm-bundle.tar
[root@centos-linux ~]# tar xvf mysql-5.7.13-1.el7.x86_64.rpm-bundle.tar
mysql-community-test-5.7.13-1.el7.x86_64.rpm
mysql-community-embedded-5.7.13-1.el7.x86_64.rpm
mysql-community-embedded-compat-5.7.13-1.el7.x86_64.rpm
mysql-community-server-5.7.13-1.el7.x86_64.rpm
mysql-community-client-5.7.13-1.el7.x86_64.rpm
mysql-community-common-5.7.13-1.el7.x86_64.rpm
mysql-community-server-minimal-5.7.13-1.el7.x86_64.rpm
mysql-community-embedded-devel-5.7.13-1.el7.x86_64.rpm
mysql-community-devel-5.7.13-1.el7.x86_64.rpm
mysql-community-libs-compat-5.7.13-1.el7.x86_64.rpm
mysql-community-libs-5.7.13-1.el7.x86_64.rpm
mysql-community-minimal-debuginfo-5.7.13-1.el7.x86_64.rpm

3、安装

依次执行（几个包有依赖关系，所以执行有先后）下面命令安装

[root@centos-linux ~]# rpm -ivh mysql-community-common-5.7.13-1.el7.x86_64.rpm
[root@centos-linux ~]# rpm -ivh mysql-community-libs-5.7.13-1.el7.x86_64.rpm
[root@centos-linux ~]# rpm -ivh mysql-community-client-5.7.13-1.el7.x86_64.rpm
[root@centos-linux ~]# rpm -ivh mysql-community-server-5.7.13-1.el7.x86_64.rpm

4、数据库初始化

在 *nix 系统中，为了保证数据库目录为与文件的所有者为 mysql 登陆用户，如果你是以 root 身份运行 mysql 服务，需要执行下面的命令初始化

mysqld --initialize --user=mysql

如果是以 mysql 身份运行，则可以去掉 --user 选项。

另外 --initialize 选项默认以“安全”模式来初始化，则会为 root 用户生成一个密码并将该密码标记为过期，登陆后你需要设置一个新的密码，而使用 --initialize-insecure 命令则不使用安全模式，则不会为 root 用户生成一个密码。

这里演示使用的 --initialize 初始化的，会生成一个 root 账户密码，密码在log文件里

[root@centos-linux ~]# cat /var/log/mysqld.log
2016-07-16T07:56:38.282824Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2016-07-16T07:56:38.422114Z 0 [Warning] InnoDB: New log files created, LSN=45790
2016-07-16T07:56:38.449315Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2016-07-16T07:56:38.457910Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: d3261dbf-4b2a-11e6-86ef-001c4260563f.
2016-07-16T07:56:38.458976Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2016-07-16T07:56:38.459524Z 1 [Note] A temporary password is generated for root@localhost: hm9dKgzQdm:W

上图里的最后一行则给出了生成的密码，现在就可以启动数据库了，然后使用上面的密码登陆。

[root@centos-linux ~]# systemctl start mysqld
[root@centos-linux ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.13

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>

5、修改 root 密码

该密码被标记为过期了，如果想正常使用还需要修改密码

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

以前的 password()函数将会被抛弃，官方建议使用下面的命令来修改密码

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'new_password';

同时，如果你设置的密码过于简单也会报错。

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY '123';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

具体关于设置密码的规则，可以看这一篇文章。

这里我们注意设置密码 长度要大于8，同时要有数字，大小写，特殊字符。