When I was still relatively new to my day job as a computer programmer I was assigned a task by my boss. That wasn’t anything particularly out of the ordinary. I’ve been assigned many tasks by my boss both before that day and since. But this particular task stands out in my memory. I was supposed to go into the production database - a.k.a. the place that stored all of the data that our clients were actively using - and make a change to a certain subset of the users. Knowing that I was working with THE REAL DATA I carefully crafted my query, checked it over a second time, and then ran it.