> My question question from MySQL 4.0.22: is it okay that a null interger
> equal to any value. I am not sure the table structure matters but in case
> I included it.
> I did not expect that null was not not-equal to 1. Cursory testing seems
> indicate that a null integer field is not not-equal to any specific value.
> this is the "known" behavior, I would suggest that this behavior be added
> section A.5.3. Testing the field=1 works as I would expect, that is the
> value is not equal to 1.
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,
Database Workbench - tool for InterBase, Firebird, MySQL, Oracle & MS SQL
Database development questions? Check the forum!