输入命令sudo apt-get install mysql-server-5.6
第一个问题的解决方式：https://help.aliyun.com/knowledge_detail/41124.html
1.Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
mysql-server-5.6 : Depends: mysql-common (>= 5.6.22-1~) but 5.5.58-0ubuntu0.14.04.1 is to be installed
E: Unable to correct problems, you have held broken packages.
2.
2017-11-29 07:09:25 0 [Warning] Using unique option prefix key_buffer instead of key_buffer_size is deprecated and will be removed in a future release. Please use the full name instead.
2017-11-29 07:09:25 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2017-11-29 07:09:25 0 [Note] /usr/sbin/mysqld (mysqld 5.6.33-0ubuntu0.14.04.1) starting as process 9131 ...
start: Job failed to start
invoke-rc.d: initscript mysql, action "start" failed.
dpkg: error processing package mysql-server-5.6 (--configure):
subprocess installed post-installation script returned error exit status 1
E: Sub-process /usr/bin/dpkg returned an error code (1)
第一个问题解决了。第二个问题搞了半个下午还是没弄成（我运行的时候根本就sock文件），最好卸载直接装成了5.5的了。
