Odd SQL behavior, I'm wondering why this works the way it does.
- by Matthew Vines
Consider the following Transact sql.
DECLARE @table TABLE(val VARCHAR(255) NULL)
INSERT INTO @table (val) VALUES('a')
INSERT INTO @table (val) VALUES('b')
INSERT INTO @table (val) VALUES('c')
INSERT INTO @table (val) VALUES('d')
INSERT INTO @table (val) VALUES(NULL)
select val
from @table
where val not in ('a')
I would expect this to return
b, c, d, NULL
but instead it returns
b, c, d
Why is this the case? Is NULL not evaluated? Is NULL somehow in the set 'a'?
