1）mysql 安裝
1.安裝MySQL YUM資源庫
[root@localhost ~]# yum localinstall https://dev.mysql.com/get/mysql57-community-release-el7-8.noarch.rpm
2.此時可以使用以下命令搜索到所需安裝mysql
[root@localhost ~]# yum search mysql
3.安裝
[root@localhost ~]# yum -y install mysql-community-server.x86_64
4.啟動數據庫
[root@localhost ~]#systemctl start mysqld（centos7上使用systemctl,其他版本的centos可能使用service，我一直用的centos7）
5.設置開啟自啟動
[root@localhost ~]#systemctl enable mysqld
6.安裝完成
2）mysql初始密碼問題（適用於mysql5.7以上版本）
1.由於我上一個數據庫卸載沒完全的問題，所以cat /var/log/mysqld.log|grep temporary並不能獲得初始密碼
[root@localhost ~]# cat /var/log/mysqld.log|grep temporary
2019-12-07T01:23:03.644746Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
2.刪除殘留數據
[root@localhost ~]# rm -rf /var/lib/mysql
3.重啟
[root@localhost ~]# systemctl restart mysqld
4.再獲得初始密碼
[root@localhost ~]# cat /var/log/mysqld.log|grep temporary
2019-12-07T01:23:03.644746Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
2019-12-07T01:29:08.103192Z 1 [Note] A temporary password is generated for root@localhost: *oEsYdO_x9fj
2019-12-07T01:29:10.501031Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
此時可以得到初始密碼為*oEsYdO_x9fj
5.進入數據庫
mysql -uroot -p*oEsYdO_x9fj
6.重設密碼
mysql> set password='NewPassword';
或者
mysql> ALTER user 'root'@'localhost' IDENTIFIED BY 'NewPassword';
7.完成。