Database modeling is closer to library science than computer science. No one is impressed by a librarian who gets creative and files cookbooks under “G” for “Gourmand.” The best catalog system is where everything is in an obvious place, where everything conforms to expectations. As Alec Baldwin’s database consultant explained to a team of application developers he was brought in for the day to train in Glengarry Glen Ross, it comes down to three simple letters, LCD: