You made a mess

Probably you updated from libc5 to libc6.
So now, the only thing that could be working on your debian is mysql-server.
NEVER upgrade the libc without taking care.
What you should have done is to build the package yourself because probably the source package doesn't have the dependency on the libc and it would have adapted to your libc5 (or old libc6)
something like
apt-get build-dep mysql-server <-- gets the dependencies for compiling
apt-get source mysql-server <-- gets the source
fakeroot dpkg-buildpackage binary <-- build a package from source
There is no need to get the tar.gz source.
Otherwise your system (a real system, not with 3 or 4 programs installed) is a mess: which library is still needed, whats this file doing here, all these questions that you don't ask yourself with apt.
You can always revert your mess by downloading the old libc<xxx>.deb package that you had. Then you have to boot by any means (livecd for example), and install the .deb with dpkg with the option to tell it to install to your debian, not to the / of the livecd. Happened to me once and everything was in order after a few minutes, no need to reinstall.