由于电脑是32位系统的centos6.5，搜罗了网上一圈都没有很好的解决详细的流程，所以这里给罗列一下：
首先要到官网下载好四个rpm包，如下：

①下载linux版本的mysql

mysql下载官网：https://dev.mysql.com/downloads/
点 MySQL Community Server==》再点击选32位的

点击右上角Looking for the latest GA version?选版本，我的是5.7.30

安装之前要先卸载原来的mysql：
1.查看是否安装Mysql
[[email protected] module]$ rpm -qa | grep -i mysql
MySQL-client-5.6.24-1.el6.x86_64
MySQL-server-5.6.24-1.el6.x86_64
2.查看MySQL服务是否启动，关闭
[[email protected] module]$ sudo service mysql status
[sudo] password for atguigu:
MySQL running (2681) [确定]

[[email protected] module]$ sudo service mysql stop
Shutting down MySQL… [确定]
3.卸载MySQL安装的组件
[[email protected] module]$ sudo rpm -e MySQL-server-5.6.24-1.el6.x86_64
[sudo] password for atguigu:
[[email protected] module]$ sudo rpm -e MySQL-client-5.6.24-1.el6.x86_64
4.查找并删除MySQL相关的文件
[[email protected] module]$ whereis mysql
mysql: /usr/lib64/mysql

[[email protected] module]$ sudo find / -name mysql
/var/lib/mysql
/var/lib/mysql/mysql
/usr/lib64/mysql

[[email protected] module]$ sudo rm -rf /var/lib/mysql
[[email protected] module]$ sudo rm -rf /usr/lib64/mysql

把它复制到linux下，无需解压，直接安装：
[[email protected] mysql-libs]# rpm -ivh mysql-community-common-5.7.30-1.el6.i686.rpm
[[email protected] mysql-libs]# rpm -ivh mysql-community-libs-5.7.30-1.el6.i686.rpm
[[email protected] mysql-libs]# rpm -ivh mysql-community-client-5.7.30-1.el6.i686.rpm
[[email protected] mysql-libs]#rpm -ivh mysql-community-server-5.7.30-1.el6.i686.rpm

这里注意先要安装common 和lib 再安装client和server，他们是会相互依赖的
安装好后先查看 service mysql status，然后居然报：
mysqld：未被识别的服务
所以我换一种方式启动
先修改 vim etc/my.conf 文件把 basedir=/xxx/xxx注释掉

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
#basedir=/usr/share/mysql

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

然后把datadir下路径下数据干掉：[[email protected]]rm -rf /var/lib/mysql/*
再进行初始化：[[email protected]] mysqld --initialize 直接回车，执行初始化…稍等一会就OK了
再启动：service mysqld start
查看状态：service mysqld status
安装好后由于5.6以后是无法通过cat /root/.mysql_secret命令查看到密码的所以要到 log-error指定的路径 cat /var/log/mysqld.log 文件里找到如下一行里：2020-05-13T05:58:45.920596Z 1 [Note] A temporary password is generated for [email protected]: gwsxk?sD?9zZ
其中： gwsxk?sD?9zZ 就是mysql自动生成的密码

最后登录mysql：[[email protected]] mysql -uroot -pgwsxk?sD?9zZ

最后再更改密码就可以了
3．修改密码
mysql>SET PASSWORD=PASSWORD(‘000000’);