Hi@akhtar,
You need to install the software for MySQL. You can check the software name using the below-given command. 
$yum whatprovides mysql 
Loaded plugins: product-id, search-disabled-repos, subscription-manager
This system is not registered with an entitlement server. You can use subscripti                                                                                        on-manager to register.
Repository 'dvd' is missing name in configuration, using id
Repository 'open' is missing name in configuration, using id
1:mariadb-5.5.56-2.el7.x86_64 : A community developed branch of MySQL
Repo        : dvd
Matched from:
Provides    : mysql = 1:5.5.56-2.el7
3:mariadb-10.1.20-2.el7ost.x86_64 : A community developed branch of MySQL
Repo        : open
Matched from:
Provides    : mysql = 3:10.1.20-2.el7ost
3:mariadb-10.1.20-2.el7ost.x86_64 : A community developed branch of MySQL
Repo        : @open
Matched from:
Provides    : mysql = 3:10.1.20-2.el7ost
You can see the software name above. Now install this software in your system.
$ yum install mariadb-5.5.56-2.el7.x86_64
Hope this helps!
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Thanks.