I've recently started playing with a Home Assistant set up and came across Snips (https://snips.ai/). A bunch of Raspberry Pis with microphones running Snips is what I'm looking to try next. IMO, the offline/on-device processing is a key differentiator.
OP is right. You can get qualified on multiple aircraft types, but to maintain currency is a different topic altogether. In the US for example, at least for private pilots, you need at least 3 take offs and landings in the last 90 days in the aircraft (category/class/type-rating) to be able to carry passengers. Then there's extra requirements for night currency and instrument rating currency.
I would imagine the airlines have even tougher currency requirements. That said, it's probably possible to maintain currency in several aircraft types depending on the frequency and how the jobs are scheduled.
But are they common with the light yields and spectrum width of the GP? If so, can you cite where they're for sale? No hydro growth shops can source any at significantly better prices than the one in GP, and with higher energy use to boot. You cannot just go to IKEA, get a couple of meters of their bottom-price LEDs and start your indoor grow operation with that. Believe me, 1000's of people have tried and failed; forums are full of reports. (Mostly from people growing marijuana of course, but also chili peppers, which is my use case).
I actually have a grow shop around the corner from where I live who have chili peppers in their display grow boxes (because they can't grow marijuana there for legal reasons), and they use MH lamps still; if there would be a cheaper way to grow, they'd switch in a heartbeat, because indoor growing is about squeezing every last drop of efficiency from your setup (although it's been a while since I've been there to be honest, and I did see them advertise a LED grow light a few weeks ago, but still not at prices much lower than GP).
There are benefits for marking a row as deleted w/ a boolean column though. Undo-ing deletes would be easy to implement, and retaining references to deleted records would be simple as well.
The solution the problem you described would be to use a surrogate key column (typically a UUID/auto-increment), and not natural keys.
There are reasons for everything in the database. Undo and historical records were the primary use case.
All tables had a unique, integer primary key.
However, if you want to enforce a uniqueness constraint across your data [eg. UNIQUE(name, location)], the constraint breaks when you introduce the boolean deleted column [and UNIQUE(name, location, deleted) does not provide the appropriate semantics]. The application semantics must be provided at some other level than SQL column constraints.
