记录CentOS7.X版本下安装MySQL5.7数据库
设置rpm下载目录在/opt目录下新建一个目录存放mysql
cd /opt
sudo mkdir mysql
下载MySQL的源
wget http://repo.mysql.com/mysql57-community-release-el7-8.noarch.rpm
如果在这之前没有提示-bash: wget: command not found，那么还得先安装wget
sudo yum install wget
安装MySQL的rpm
sudo rpm -ivh mysql57-community-release-el7-8.noarch.rpm
安装MySQL
sudo yum install mysql-server
在这步中只需要一直y然后回车就行，数据库就安装好了，现在进行连接：
mysql -uroot -p
root
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
这是/var/lib/mysql权限问题，修改MySQL权限为当前用户
sudo chown -R xxx:xxx /var/lib/mysql
xxx为当前的用户名以及所属组
重启MySQL服务
service mysqld restart
密码输入root即可
如果还不行的话通过这个命令获得初始密码
cat /var/log/mysqld.log | grep password
其中A temporary password is generated for root@localhost: bGlY?13TtFyX–：后面的就是初始密码；登陆进去之后先不做其他操作，作如下操作：
set global validate_password_policy=0;
set global validate_password_length=4;
设置密码
alter user 'root'@'localhost' identified by 'root';
自此CentOS安装MySQL5.7就完美安装了
mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.20 MySQL Community Server (GPL)
Copyright (c) 2000, 2017, 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>
