To @@ERROR is human, too

I started writing a short blog post about a particularly egregious example of bad transaction handling I encountered the other day, and the thing just ran away with me. First it became a long post, then a couple of examples were added and before I knew where I was I'd gone 6 pages further and it had become a full-blown article to explain the very basics of how error trapping, error handling and transaction handling works in SQL Server (PDF, 252KB).