阿里云CentOS7.3安装MySQL以及配置远程连接

CentOS7默认数据库是MariaDB, 但是我用的是MySQL。

1、查看当前是否有MySQL进程

rpm -qa|grep -i mysql

有的话则需要kill掉，再删除；没有直接到第2步

pkill -9 mysqld
yum -y remove mysql-community-client-5.6.38-2.el7.x86_64

卸载不掉的用rpm -ev mysql-community-client-5.6.38-2.el7.x86_64
依次卸载，直到没有

2、创建目录，下载MySQL5.7

mkdir /usr/local/mysql
cd /usr/local/mysql
wget http://repo.mysql.com/mysql57-community-release-el7-8.noarch.rpm
rpm -ivh mysql57-community-release-el7-8.noarch.rpm
yum -y install mysql-server

根据步骤安装就可以了

默认配置文件路径：
配置文件：/etc/my.cnf
日志文件：/var/log/var/log/mysqld.log
服务启动脚本：/usr/lib/systemd/system/mysqld.service
socket文件：/var/run/mysqld/mysqld.pid

3、配置my.cnf：

vim /etc/my.cnf

[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
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
server_id = 1
expire_logs_days = 3

# 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

注意：安装完成后，密码为随机密码，需要重置密码。

4、启动服务，修改密码

service mysqld restart
grep "password" /var/log/mysqld.log

可以在信息中查看到一串临时密码，使用临时密码登录，再修改密码

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mysql -u root -p

进入后需要重置密码（5.7.20为了安全密码，必须包含数字字母符号）

// Root!!2018为参考密码
alter user 'root'@'localhost' identified by 'Root!!2018';
// 刷新
flush privileges;

5、开放远程连接

// 赋予root用户所有权限，远程登录密码是Root!!2018
grant all privileges on *.* to 'root' @'%' identified by 'Root!!2018';
// 刷新
flush privileges;

退出MySQL。

6、允许服务自启动

chkconfig --add mysql
chkconfig mysql on

7、开放防火墙端口
在CentOS 7或RHEL 7或Fedora中，防火墙由FirewalID来管理

通过systemctl status firewalld查看FirewalID状态，发现当前是dead状态，即防火墙未开启。
通过systemctl start firewalld开启防火墙，没有任何提示即开启成功。
执行firewall-cmd --permanent --zone=public --add-port=3306/tcp --permanent，提示success
（–permanent永久生效，没有此参数重启后失效）
执行firewall-cmd --reload，提示success

或者关闭防火墙：systemctl stop firewalld

最后一步：