1.解除安裝  先停掉mysql程序   沒有安裝過的可以直接跳過
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
解除安裝不掉的用 rpm -ev
依次解除安裝 直到沒有

2.採用yum方式安裝mysql-server

[[email protected] ~]# cd /usr/local/src/
[[email protected] src]# wget http://repo.mysql.com/mysql57-community-release-el7-8.noarch.rpm
[[email protected] src]# rpm -ivh mysql57-community-release-el7-8.noarch.rpm
[[email protected] src]#  yum -y install mysql-server

預設配置檔案路徑：
配置檔案：/etc/my.cnf
日誌檔案：/var/log/var/log/mysqld.log
服務啟動指令碼：/usr/lib/systemd/system/mysqld.service
socket檔案：/var/run/mysqld/mysqld.pid

3.  啟動mysql服務

service mysqld restart

4.重置mysql的登陸密碼
不過安裝完成後，密碼為隨機密碼，需要重置密碼。

 重置密碼:
[[email protected] src]# grep "password" /var/log/mysqld.log
2018-11-04T01:50:24.990787Z 1 [Note] A temporary password is generated for [email protected]: Zu0jQ5h)#sW%
2018-11-04T01:50:49.512413Z 2 [Note] Access denied for user 'root'@'localhost' (using password: NO)

可以看到  輸入 mysql -u root --password

  然後輸入密碼 進入
第一次登陸 ，需要重置密碼
mysql> set password for [email protected] = password('mypassword')