Hello,
I'm a long time Postgres user who uses MySQL when I have to. I recently
ran into an issue with MySQL where this construct didn't do what I expect:
WHERE date_column = NULL
I expected it to work like "date_column IS NULL" like it does it
Postgres 7.0.2, but instead it returned an empty result set.
After conversing with some folks on the MySQL list, it was mentioned that:
* "NULL is *NOT* a value. It's an absence of a value, and doing *any*
comparisons with NULL is invalid (the result must always be NULL, even
if you say "foo = NULL")."
* Postgres handling is non-standard (even if it's intuitive.)
My questions then are: 1.) What IS the standard for handling NULLs? and
then 2.) If Postgres handling is different than the standard, what's the
reason?
To me, having " = NULL" be the same as " IS NULL" is intuitive and thus
useful, but I also like appeal of using standards when possible. :)
Thanks!
-mark
http://mark.stosberg.com/