@nixCraft sure, you can even run multiple versions of Mysql side by side if you really have to. Just bind them to different ports. However, to prevent yourself a lot of dependency hell in your package manager, it is certainly advisable to put each database server in its own container. Docker, LXC, LXC, or whatever container system you prefer.
@nixCraft printed out on paper, sorted in binders. Multiple copies, with at least one every three months for active projects. (not a joke by the way, I helped cleaning up a cabinet a couple of years ago, filled with printouts. We threw out many meters of printed pages of code. Some of it was even clearly dot matrix printer paper) And before that of course on punch cards, with comments written on the actual cards.
@nixCraft I've had the same fear, but 11 seems to run most things that work with 8. Java versions are like black magic however. For java things I really need to work I stopped relying on system-provided java a long time ago. There are a bunch of those pre-packaged JRE /JDK versions, but I landed on "azul". They have them for win/mac/lin, with FX if needed, and also x86 and arm versions. https://www.azul.com/downloads/#zulu Worth checking out, if you want to skip the "will my java stuff work?" question!
@nixCraft make regular backups of your coding files. Do this by making a copy of the file you are coding in, preferably in the same directory for easy recovery, and name them like this: originalfilename_first-draft_friday_17th.origextension, originalfilename_second-version_fridayafternoon_17th.origextension, originalfilename_almost-working_friday_17th:8:25PM.origextension, originalfilename_final-segfault_friday_17th-verylate.origextension, etc...
@nixCraft any real dev will try the second test with a filled glass, preferably with something that stains well, just like "hello from line X" print statements
@nixCraft until somebody decides to rewrite the cobol/perl stuff into python, and adds comments like: # the old script called make twice in a row here, no idea why but let's roll with it