RP Scripting Help (Damn SQL)

So I have problems working with sql, it confuses me and makes me take 100000000E142 breaks when coding lua. Nothing gets done, I know it’s not that confusing to you guys - but I hate it, don’t yell at me (NOTE: I hate programming sql, not sql itself, it’s a very powerful tool). I need systems for the following things for my rp server I’ve been working on:

  1. Inventory system: I’ve seen these on more and more servers lately so it shouldn’t be too hard to track one down. I’ll probably be able to find one but I’ll post it here cause what the hell?

EDIT: Inventory system found.

  1. Banking system: I made the entities, scripted the gui, made the atms place themselves on the map at startup. But when I got to the REAL programming like: withdraws, deposites, storing all that to sql, getting all that from sql, and especially having every players interest go up whether they are on the server or not. All that confused the hell out of me - and made me stop coding for a while.

EDIT: Got this scripted thanks to Donkie’s help and real time tutorials ^^

  1. This one is really important (and confusing >.>); Car system: I want players to be able to buy cars, but not for some stupid default rp price like 2k every time they get on. I’m talking like perp or darklands. EXPENSIVE, but when players buy them, I need an npc to remember that they bought it. This went a step further into sql that I couldn’t even begin to comprehend and I was just like DAMN I’ll do that when I get better.

Well I’m not getting better at SQL cause I can’t seem to get the basics like the bank (which isn’t basic basic but shouldn’t be too hard.). Can anyone help me with any of these?

EPICEDIT™: Not adding the car dealer due to vehicles causing tons of lag. The other two are done. Thanks a ton to dorifox, wizzy, and donkie ^^