Thanks Martijn - that is a clear explanation of the philosophy. I did not get it
from the examples and the manual.
On Mon, 19 Sep 2005, Martijn Tonies wrote:
> Hello Doug,
> > My question question from MySQL 4.0.22: is it okay that a null interger tests
> > equal to any value. I am not sure the table structure matters but in case
> it is
> That's because NULL is NOT a value (not the logical "not" ;) ... It's a
> Any column can have two states: either NULL or NOT NULL.
> When a column is "not null" it can have values suitable for it's given
> (eg: all integer values).
> If there's no value (NULL), how can you compare it?
> Think of "NULL" as "unknown". Is 2 equal to "unknown"? I don't know, so
> the result is "unknown", hence, NULL.
> Hope this helps,
> With regards,
> Martijn Tonies
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