From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Thomas Lockhart <lockhart(at)alumni(dot)caltech(dot)edu> |
Cc: | Magnus Hagander <mha(at)sollentuna(dot)net>, Tatsuo Ishii <t-ishii(at)sra(dot)co(dot)jp>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: comparing rows |
Date: | 2000-08-03 14:07:24 |
Message-ID: | 7503.965311644@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Thomas Lockhart <lockhart(at)alumni(dot)caltech(dot)edu> writes:
> btw, it appears that SQL99 (haven't checked SQL92) specifies that
> test=# select (1,2,3) = (1,2,null);
> ?column?
> ----------
> (1 row)
> should return FALSE, not NULL.
What? If so, they broke it pretty badly. This should be equivalent to
1 = 1 AND 2 = 2 AND 3 = NULL, which should reduce to TRUE AND TRUE AND NULL,
which should reduce to NULL. Anything else is not self-consistent.
>> Summary of MS:
>> When it runs in ANSI mode, null != null.
> *sigh* If it actually *had* an ANSI mode, then "foo = NULL" would be
> rejected. Period.
Well, mumble, that is an overly literal interpretation of the spec if
you ask me. It is not unreasonable to allow NULL as a literal constant,
especially since it doesn't create any issues that you can't get to with
100%-plain-vanilla-SQL92 constructs like
CASE WHEN TRUE THEN NULL END
Where MS blew it was in not following SQL92-compatible semantics of
operations on nulls. (We can't throw *too* many stones, since we had
a number of problems with logical ops on nulls too, up till 7.0 ...)
> afaict the option will be "M$" vs "published standards" support, and it
> seems the wrong way to head.
I don't want an option either. I want to change our code (back to) SQL
compliant semantics of NULL comparisons, ie remove the parser kluge.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Magnus Hagander | 2000-08-03 14:10:06 | RE: comparing rows |
Previous Message | Magnus Hagander | 2000-08-03 14:00:37 | RE: comparing rows |