centos7中安装mysql - mysql - 数据库 - 技术设计

环境：centos7.3
mysql：5.7

数据库安装

	# 下载 mysql5.7 源安装包
	wget http://dev.mysql.com/get/mysql57-community-release-el7-8.noarch.rpm
	# 安装 mysql 源
	yum localinstall -y mysql57-community-release-el7-8.noarch.rpm
	# 安装 mysql 服务
	yum install mysql-community-server

mysql 服务管理

	# 启动 mysql 数据库
	systemctl start mysqld.service
	# 设置 mysql 的开机启动
	systemctl enable mysqld.service
	# 重启 mysql 服务
	systemctl restart mysqld.service
	# 查看 mysql 的服务状态
	systemctl status mysqld.service

初始密码
mysql 安装完成后是有初始密码的，不过这个密码是随机的，用户名是默认的 root，这个密码在 mysql 的日志文件中。
centos7.3 安装完 mysql 后 log 文件的默认地址在：

/var/log/mysqld.log

mysql 的配置文件默认在：

/etc/my.cnf

可以从 mysql 的配置文件下查看到一些有用信息：

	vim my.cnf
	# For advice on how to change settings please see
	# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html

	[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

	# 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

可以从配置文件中找到数据文件的存放目录：datadir=/var/lib/mysql
日志文件地址：log-error=/var/log/mysqld.log
pid 文件：pid-file=/var/run/mysqld/mysqld.pid
前面一大堆的铺垫，就为了要说 mysql 的初始密码存放在了 log 文件中。

	vim /var/log/mysqld.log

	……
	2019-01-28T09:56:33.184635Z 1 [Note] A temporary password is generated for root@localhost: T_h>H&giP5OA
	……

找到大致内容是这样的一行代码，最后的关键词是：password is generated for root@localhost: T_h>H&giP5OA，这最后的内容就是密码了。结下来就是改了。

	# 通过默认的用户名、密码登录数据库
	mysql -u root -p
	# 输入密码
	T_h>H&giP5OA #密码输入时不显示的，不要因为没有看见而以为没有输入成功

	# 改密码
	ALTER USER 'root'@'localhost' IDENTIFIED BY '新密码';