>Also please understanding aliasing.
With ISAM files (dbase, clipper, etc files), one simply duplicated the file definition in code and pointed it to the same file on disk. Them were the days.
I'd also add, be aware of the time it takes to build and deliver views and stored procedures result sets, some of them kill the server, but at least sql servers only deliver the results over the network, unlike ISAM files which copied the entire set of files down to the workstation in order to then build the "view". Talk about congest the network.
TO the OP, I'd pick something that interests you and then look at what languages are being used in that domain.
Whilst its common to hear about the pythons, dotnet, java languages, in practice, there are many languages out there many being used in niche applications. Not all recruitment agencies deal with niche programming languages, so recruitment can take place in other ways, like via internet forums and user groups.
For example, one of the global companies that makes credit and debit cards uses this parser to control its manufacturing process. https://en.wikipedia.org/wiki/GOLD_(parser)
They have different machines for making the card, programming the chip, printing and embossing, and all these different machines use different programming languages to control them and there are sometimes different machines in different parts of the world to contend with, because the banks like to get your replacement card out to you overnight anywhere or nearly anywhere in the world.
If you look on the back of your debit/credit card, you can usually find who manufactured your card.
So if you want to go mainstream, life might not be as rewarding. If worst comes to the worst, get a job working for security services, they like to train people up and you'll get an insight into how they think and operate, but you wont be able to tell anyone, its a contract for life which you might not want.