But not in one giant queryable SQL table.
I'd worry about parallelized spearfishing attacks across multiple stores, "Good Morning DEF, have I reached store number 12345 cash handling office? OK good to hear, this ABC at walmart corporate IT calling back about that trouble ticket your coworker XYZ entered about your store in Springfield, is XYZ at work now? Oh OK, well, anyway the ticket says XYZ is having trouble accessing the credit card portal, the ticket says you're trying to log in using the password of "password2", and back at HQ I can't log in using that password either so I'm planning on resetting her password, which will completely lock her out of the system for at least a week, unfortunately, but that's how ... Oh wait, you say there's a post it note on the monitor that her password is actually "ilovejustinbeiber", hold on a moment let me try that. How about that, it does work. Hey thanks for helping out, gonna save a lot of trouble for everyone. I'm not going to reset XYZ's password since it does work, I'll just close out the ticket with "can't reproduce problem", whoever took the ticket here couldn't enter the data right and obviously whatever problem there was is fixed now. Have a nice day out there in Springfield, Make Walmart Great Again (or whatever it is they say) Bye!"
Or some team calls like twenty electronics departments and tells all of them to toss all their ipad stock into a large shipment box because they were shipped with faulty batteries while reading back all the info they gathered to build trust, then let them know a courier from UPS (fake brown uniform) will present a (fake) ID and pick up that box of ipads in an hour and they can expect replacements air shipped later that day. Remind the employee to make sure they sign and save the (fake) return receipt. Imagine what a large team could do with a phone that takes pictures, snapping serial numbers of boxes on the shelf and a half hour later reading the serial number list back to the clerk over the phone.
This is all old stuff, but the advantage is you can parallelize it. If "they" hit one store every night there would be emergency emails printed out and taped up and handed out by the next week, but if you run this right you could do maybe 200, 300 stores.
Even better if a competitor paid you to pull this off on Black Friday when half the IT staff took the day off anyway and all you need is to sow chaos to make money. Or do this the day before earnings are announced to really mess with them financially.