On Tue, Apr 26, 2005 at 03:48:44PM -0500,
Scott Marlowe <smarlowe@xxxxxxxxxxxxxxxxx> wrote a message of 26 lines which said:
Here's a quote from the SQL1992 spec that's VERY clear:
Yes, PostgreSQL is right and implement the standard. Now, what's the rationale for the standard? I understand it for a single column but, for several columns, it should be still possible to have different tuples, such as (3, NULL) and (5, NULL) for instance.
The value of (3,NULL) isn't well-defined. In particular, you can't say that (3,NULL) = (3,NULL) since NULL means not-known. The fact that part of the value is not known means the value as a whole is not known.
-- Richard Huxton Archonet Ltd
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