CentOS 7.4下使用yum安装MySQL5.7.20

1.卸载先停掉mysql进程没有安装过的可以直接跳过

pkill -9 mysqld

 rpm -qa|grep -i mysql

用命令 yum -y remove

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

卸载不掉的用 rpm -ev

依次卸载直到没有

2.下载mysql的repo源这个安装的mysql5.7.20 /纠正一下，这源下载的是最新的版本 **/

[root@localhost ~]# cd /usr/local/src/
[root@localhost src]# wget http://repo.mysql.com/mysql57-community-release-el7-8.noarch.rpm

[root@localhost src]# rpm -ivh mysql57-community-release-el7-8.noarch.rpm

[root@localhost src]# yum -y install mysql-server

（也可以指定安装目录 yum --installroot=/usr/local/mysql --releasever=/ -y install mysql-server ）我没试，这样装环境变量配置都不用你管，装上直接启动就行。安装路径是默认的。

一路 y

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

默认的配置文件/etc/my.cnf如下：

# 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
"/etc/my.cnf" 27L, 960C                                    27,1          Bot
# 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

不过安装完成后，密码为随机密码，需要重置密码。

3. 启动mysql服务

service mysqld restart

重置密码

[root@localhost ~]# grep "password" /var/log/mysqld.log

可以看到输入 mysql -u root -p 密码进入第一次登陆，需要重置密码要不什么也不能操作

接下来重置密码：5.7.20 为了安全，密码必须包含数字字母符号

alter user 'root'@'localhost' identified by 'Root!!2018';

最后记得刷新权限；

flush privileges

也可以直接再添加新用户

CREATE USER ‘root’@‘%‘ IDENTIFIED BY ‘您的密码‘;

grant all on *.* to 'root001'@'%' identified by 'Root@@' with grant option;

增加root用户指定可以任意IP登录，如果想限制只能让指定IP登录请把%替换成IP地址