data-konzept

'With all the trouble NULLs cause…

You’d think people would be more inclined to avoid them. Slap a NOT NULL constraint and a default value on your column and call it a day. I’m perfectly fine with bizarro world canary values. If it’s an integer column, some really high (low?) negative number. If it’s date-based, why not have it be the lowest value your choice accomodates?

But no, no, no. Instead of stopping the bleeding, developers tend to just avoid getting blood on the new carpet. Some of the worst performing queries I see have ISNULL(something, '') = ISNULL(somethingelse, '') either in the JOIN or WHERE clause. Still. To this day. In the age of the hoverboard, people are still putting functions where they don’t belong. And I know they have the internet.'...

https://www.brentozar.com/archive/2016/03/the-joy-of-joining-on-nulls/