[root@backup02 ~]# mysql -u root -p
Enter password:
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 391
Server version: 5.5.68-MariaDB MariaDB Server  

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.  

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.  

MariaDB [(none)]> select version();
+----------------+
| version()      |
+----------------+
| 5.5.68-MariaDB |
+----------------+
1 row in set (0.00 sec)  

MariaDB [(none)]>    

yum -y update  

vim /etc/yum.repos.d/MariaDB10.repo  

[mariadb]
name = MariaDB baseurl = http://yum.mariadb.org/10.3/centos7-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1  

systemctl stop mariadb  

yum remove mariadb-server mariadb mariadb-libs  

yum clean all  

yum -y install MariaDB-server MariaDB-client  

systemctl start mysql  

systemctl enable mysql  

mysql_upgrade   Or   mysql_upgrade -u root -p  

mysql -u root -p  

[root@backup02 ~]# mysql -u root -p
Enter password:
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 27
Server version: 10.3.28-MariaDB MariaDB Server  

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.  

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.  

MariaDB [(none)]>