The Despicable NULL

NULL in SQL is not just a technical feature – it's a full-fledged database saboteur. It disguises itself as a harmless “absence of a value”, but in reality creates logical paradoxes that break business logic. Different DBMSs handle it in their own ways: sometimes it's unique, sometimes equal to an empty string, and sometimes it is not even equal to itself. As a result, queries start lying, reports show fake analytics, and money quietly leaks through data holes. The most expensive and hilarious incidents in IT history are often tied to NULL: products become free, users turn immortal, and secret agents get suddenly exposed. This talk is a collection of real nightmares that happen when NULL gets out of control. We'll explore why three-valued logic breaks conventional thinking, how to avoid financial losses, and what to do to ensure your code doesn't become the next funny story. Get ready to laugh at others' mistakes – so you don't repeat your own.