By running a select query first, you get a nice list of the rows you are going to change. If the list is the entire set, you’ll likely notice.
If it looks good, you run the update query using the same where clause.
But that’s for manual changes. OP’s update statement looks like it might be generated from code, in which case this wouldn’t have helped.
I was hoping that link would have been an example of what that would look like
https://devhumor.com/content/uploads/images/October2016/fibbonaci-indentation.jpg
Found it. It’s just obfuscated to make it harder to copy.
It looks like it’s decompiled from something, so all the variable names are missing and instead presented with whatever index they had in the binary.
But that’s just a wild guess. I don’t know what actual decompiled code looks like.
Edit: scratch that, it’s just obfuscated code to make it harder to copy.
Add a drop table statement to it while you’re at it