CentOS7环境下yum方式安装MySQL5.7
这篇博文主要是从网上摘抄的，做个记录，以后如果有同样的需求，可以直接翻自己的记录。感谢两位大神：
https://www.cnblogs.com/luohanguo/p/9045391.html
https://www.cnblogs.com/debmzhang/p/5013540.html
安装步骤
1. 从官网下载MySQL5.7的rpm包
http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
2. 如果本地使用的是windows系统，利用XFtp上传到linux服务器；
如果是mac系统，则直接使用下面的命令，将红色部分替换成服务器ip
scp mysql57-community-release-el7-10.noarch.rpm root@192.168.1.106:/opt
3. 安装Yum Repository
yum -y install ysql57-community-release-el7-10.noarch.rpm
4. 安装MySQL服务器，这一步需要一定时间
yum -y install mysql-community-server
5. 替换默认配置文件/etc/my.cnf，主要是为了将字符集改为utf8
[mysqld]
#Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
character-set-server=utf8
lower_case_table_names=1
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[client]
default-character-set=utf8
[mysql]
default-character-set=utf8
6. 启动mysql服务，并设置为开机启动
systemctl start mysqld.service
systemctl enable mysqld.service
7. 查询默认密码
cat /var/log/mysqld.log | grep password
8. 使用默认密码登录mysql
mysql -u root -p
9. 然而此时不能进行任何操作，必须先修改密码
而且密码有一定的格式限制，如果想解除限制，首先要修改系统变量值
>mysql set global validate_password_policy=0;
>mysql set global validate_password_length=1;
>mysql SET PASSWORD = PASSWORD('your new password');
>mysql ALTER USER 'root'@'localhost' PASSWORD EXPIRE NEVER;
>mysql flush privileges;
10. 退出myql，再用更新后的密码登录
11. 如果想在别的机器上远程访问这台服务器的myql，还需要开放防火墙的3306端口（做法见https://www.cnblogs.com/dubhlinn/p/11108848.html），然后在mysql命令行中对别的机器进行授权，命令为：
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'Password' WITH GRANT OPTION;
其中，%标识允许所有的ip地址通过root账号访问，如果只是想授权某个特定地址，可以替换为特定ip，Password替换为这台服务器mysql的root账号的密码。
安装位置
先查询软件包的名称，然后查找位置
rpm -qa | grep mysql
rpm -ql 包名
需要注意的是，数据库一般保存在/var/lib/mysql目录下
