On an up to date stretch, I want to install libmysqlclient-dev libmysqld-dev, but apt tells me it was not available in my sources.
/etc/opt/sources.list looks like this:
deb http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi
deb-src http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi
deb https://download.webmin.com/download/repository sarge contrib
deb-src http://raspbian.raspberrypi.org/raspbian/ jessie main contrib non-free rpi
deb-src http://mirrordirector.raspbian.org/raspbian/ wheezy main contrib non-free rpi
I wonder what could be wrong?
apt search libmysqlclient-dev
results in findingdefault-libmysqlclient-dev
... searching forlibmysqld
nothing is found - but then, I can't find anything that matcheslibmysqld
on ANY Debian based system (amd64 or arm) - so it seems you want to install something, in that case, that doesn't exist at all