In order to make my changes, I was going directly against the database, entering in my information and specifying a filter clause on my system update.
I had been working at it for over three hours, and only had about 50 records left.
I entered the information for the latest record, clicked the Execute button, and BAM!
I had forgotten to specify the filter condition, so the ENTIRE FUCKING CUSTOMER MASTER got updated! All 7700 customer records now had the same account number!
As soon as I saw the record count, I knew what happened, and man, am I pissed at myself. An entire afternoon of work flushed down the drain.
Fortunately, I took the store-to-master synchronization offline, and made a backup of the database before I started. If I can restore it, I'll effectively be back where I started, so all I've lost is this afternoon's work. However, I can't get in touch with our DBA, and he is the only one who has the restore rights on the server.
This is not something that I can leave for tomorrow morning. We have one store in the middle of a physical inventory, and my boss is anxious to see the sales results from the other stores. If I can't get this fixed real soon, like in the next hour, I'm really up shit creek.
EDIT: I was finally able to get the database restored. That still doesn't change the fact that I wasted a perfectly good afternoon, time I would have much rather spent going for a drive somewhere, walking on a trail or at the gym, or even working in the yard. I could still do the yardwork, but I'm just spent.