Hi!
I probably found an inconsistence of the working of the =
operator. Please read ahead, if you're interested.
I have two tables, let't call them a and b. They are:
a) x | y
----------------------------- 1 | 100 2 | NULL
b) y | z
----------------------------- 1 | 'hallelujah' NULL | 'hmm...'
Now let's issue this query:
select b.z from a,b where a.y=b.y;
The answer is: 'hallelujah', but it omits 'hmm...'.
Now let's issue the following:
select NULL = NULL;
The answer is: true!!!
My question is why does it omit the rows with NULL at the
first case?
However, I have a real life problem, when not all data is given in
a column, so I need a query to include the NULL=NULL rows. I can
workaround it as defining a new operator, ~=, with the
meaning "both null, or =". I did it, it works, but very slow.
So, is it an intentinal way of functioning, or it is bug somewhere?
Thanks,
Baldvin