Odd SQL behavior, I'm wondering why this works the way it does.
Posted
by Matthew Vines
on Stack Overflow
See other posts from Stack Overflow
or by Matthew Vines
Published on 2010-03-25T20:32:11Z
Indexed on
2010/03/25
20:43 UTC
Read the original article
Hit count: 219
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'?
© Stack Overflow or respective owner
