TIL: In SQL, looking for "all rows without a specific value" will not include rows containing NULL 😳 I've been using databases for 15 years and discovered this the hard way yesterday with @MarionHerisson That's really unexpected behavior on all engines: #mysql, #postgresql... https://t.co/BNDmJsrUdX

Null is not a value but a marker for an unknown value. If you find it unexpected, I would like to know your answer to this: - Monday was ☀️ - Tuesday was 🌦️ - Wednesday I don't know - Thursday was ⛈️ - Friday was⛅ Which days of the week were not raining?