Integrity

“Hey! That row shouldn’t be in that table! How the heck did that get there!? Alright, who wrote the application client filters, because you’re fired!” Good application developers know never to trust client input, but not all realize that a single app is rarely the only vector into a database. Databases don’t just preserve data with various levels of paranoia, they’re also the central nexus of a constellation of apps, scripts, APIs, GUIs, BMIs, HMOs, and STDs.