Re: why NOT NULL in PRIMARY key??

[Jigal van Hemert]

From: "Mikhail Entaltsev"

Mikhail,

> Before inserting MySQL will try to find a record with the same values.
> But since comparison with NULL value returns always FALSE
> MySQL will think that there is no such record in the table.
> After this point you will get 2 identical records in the table.

MySQL as a whole seems a bit more flexible:
a UNIQUE index allows multiple NULL values (which seems to follow the NULL
handling you describe), but with BDB table only a single NULL value is
allowed in a UNIQUE index (so MySQL seems to be able to find a NULL value in
de db).

Anyway, I gues it's just a question of following a standard and optimizing
the engine according to that standard.

Regards, Jigal.