Getting Started, had an unexplained bust attempt

I’m just getting started, and had one bust of an attempt, so now want to ask about the best way to start before I have a second bust. I restore and sell vintage fountain pens, am looking to move to AT from several Google Sheets, and a ton of duplicate entry.

The variables I am transferring over are SKU (each pen in the pipeline regardless of owner), owner code, brand, model, and other fields that are descriptive to the pen but not to be linked.
I built a master tab with all of the items, as I had them described in Sheets; then added a brand tab and a model/submodel tab; and columns in Master for Brand and Model, linked to their tabs, and linked every pen in Master to a brand and a model. I sorted a few times to make sure it all made sense, then left it for a few days. Came back last night and the models and brands had gotten confused. SKU is unique; I added a number variable to be the primary variable.
Luckily I still have the spreadsheets, but where did I go wrong? Is there a way to lock down the work once it’s saved? What happened?
Many thanks,

You can take a snapshot of your base
After which if something goes wrong you can always restore back to a earlier version.

Check out this link for a more detailed explanation.

Well, that was a save…thank you! I restored to a version that looks clean!
What it does not answer is how it happened to begin with. Is it true that a sort on a field or on multiple fields automatically sorts the entire item with all of its fields, and that (unlike a spreadsheet) one does not have to select the entire flat range to sort all of it?

Correct, a sort on a field reorders all records based on the sorted field’s contents. No need to select a specific range.

I’m not sure what would have happened that caused your base to get mangled, but I’m glad that you were able to recover what you’d done.

many thanks, appreciated. The bust is still a mystery to me as well. But, I found the snapshot and moved on.