我的CentOS版本通过从cat /etc/centos-release查看得知
CentOS Linux release 7.4.1708 (Core)
因此需要yum删除mariadb，然后安装mysql80
删除时提示如下：
正在删除:
mariadb x86_64 1:5.5.56-2.el7 @anaconda 49 M
mariadb-libs x86_64 1:5.5.56-2.el7 @anaconda 4.4 M
mariadb-server x86_64 1:5.5.56-2.el7 @anaconda 58 M
为依赖而移除:
MySQL-python x86_64 1.2.5-1.el7 @anaconda 284 k
akonadi-mysql x86_64 1.9.2-4.el7 @anaconda 9.6 k
perl-DBD-MySQL x86_64 4.023-5.el7 @anaconda 323 k
postfix x86_64 2:2.10.1-6.el7 @anaconda 12 M
qt-mysql x86_64 1:4.8.5-15.el7_4 @updates 74 k
qt5-qtbase-mysql x86_64 5.6.2-1.el7 @anaconda 79 k
redhat-lsb x86_64 4.1-27.el7.centos.1 @anaconda 0.0
redhat-lsb-core x86_64 4.1-27.el7.centos.1 @anaconda 45 k
redhat-lsb-cxx x86_64 4.1-27.el7.centos.1 @anaconda 0.0
redhat-lsb-desktop x86_64 4.1-27.el7.centos.1 @anaconda 0.0
redhat-lsb-languages x86_64 4.1-27.el7.centos.1 @anaconda 814
redhat-lsb-printing x86_64 4.1-27.el7.centos.1 @anaconda 0.0
然后yum安装mysql80 community server，就正常了。
安装步骤可以参考https://dev.mysql.com/doc/mysql-yum-repo-quick-guide/en/#repo-qg-yum-fresh-install
最后把依赖删除的有用的包yum安装回来就行了。经过实验，只有akonadi-mysql包必须依赖mariadb，无法安装，其他都可以安装回来。