NOT IN NULL

Kevin Feasel

2016-08-15

T-SQL

Jen McCown warns against NULL in NOT IN statements:

The IF statement asks: “is 1 in the collection of values (2, NULL)?” And we must say, “ah, no idea. That can’t be proven. Therefore we can’t return true.”

The value 1 cannot be determined to not be in the set of (2, NULL).

NULL is a strange bird.

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