Until now I assumed the problem of @Richard is that if a row has column ==
None, if he queries the table with column != True he expected the NULL row
to show (because in python None is different from True).
~db.table.column=False will result in a WHERE NOT column = 'F'. You don't
get any row holding column == None with that query.
What you said in your post
That would be false for False and true for True and None (NULL)
>
is what happens in python but not in any db backend, reason why it may seem
cumbersome to users accustomed to "compare" in python vs in databases.
Little recap for everybody looking at this later....
db.define_table('thenulltest', Field('thenullablefield', 'boolean'))
<Table thenulltest (id,thenullablefield)>
>>> db.commit()
>>> db.thenulltest.insert()
1L
>>> db.thenulltest.insert(thenullablefield=True)
2L
>>> db.thenulltest.insert(thenullablefield=False)
3L
>>> for row in db(db.thenulltest).select():
... print row
...
<Row {'thenullablefield': None, 'id': 1L}>
<Row {'thenullablefield': True, 'id': 2L}>
<Row {'thenullablefield': False, 'id': 3L}>
>>> for row in db(db.thenulltest.thenullablefield==True).select(): print row
...
<Row {'thenullablefield': True, 'id': 2L}>
>>> for row in db(db.thenulltest.thenullablefield!=True).select(): print row
...
<Row {'thenullablefield': False, 'id': 3L}>
##only False is extracted, None is skipped
>>> for row in db(~(db.thenulltest.thenullablefield!=True)).select(): printrow
...
<Row {'thenullablefield': True, 'id': 2L}>
##only True is extracted, None is skipped
>>> for row in db(~(db.thenulltest.thenullablefield==True)).select(): printrow
...
<Row {'thenullablefield': False, 'id': 3L}>
##only False is extracted, None is skipped
>>> for row in db(~(db.thenulltest.thenullablefield==None)).select(): printrow
...
<Row {'thenullablefield': True, 'id': 2L}>
<Row {'thenullablefield': False, 'id': 3L}>
##not None means both True OR False
>>> for row in db(db.thenulltest.thenullablefield==None).select(): print row
...
<Row {'thenullablefield': None, 'id': 1L}>
##finally, the only query that returns the "None" Field
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