Can't remove mysql-server from Ubuntu
<p>I've gotten into a bad state with MySQL on Ubuntu 16.04, so I attempted to remove it. I thought I successfully removed it with <code>apt-get remove</code>, but now whenever I do an <code>apt-get</code> or something I get the following:</p>

<pre><code>$ sudo apt-get purge mysql-client-core-5.5
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package 'mysql-client-core-5.5' is not installed, so not removed
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
 mysql-server-5.7 : PreDepends: mysql-common (&gt;= 5.5) but it is not going to be installed
                    Depends: mysql-client-5.7 (&gt;= 5.7.16-0ubuntu0.16.04.1) but it is not going to be installed
                    Depends: mysql-common (&gt;= 5.6.22-1~) but it is not going to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).
</code></pre>

<p>This seems to happen for any package I try to remove / install / etc. What's the best way to remove this?</p>