MySQL5.7 启动报错:initialize specified but the data directory has files in it. Aborting.

刚安装好的MySQL5.7.12，执行service mysqld start时报错，内容如下：
2017-02-19T07:52:53.807647Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use –explicit_defaults_for_timestamp server option (see documentation for more details).
2017-02-19T07:52:53.809065Z 0 [ERROR] –initialize specified but the data directory has files in it. Aborting.
2017-02-19T07:52:53.809095Z 0 [ERROR] Aborting

其中红色字体里面说明，mysql中的data目录已经有数据了，解决方案：

vim /etc/my.cnf，

datadir=/var/lib/mysql, 这个是data保存目录，进入/var/lib/mysql后，查看到确实有数据：

将/var/lib/mysql备份，然后重新启动mysql：