[TYPO3-mvc] Let Extbase Query check for NULL in database field

[David Schreiber]

Hello everybody,

I have two questions:

First, is there a difference between NULL and 0 in MySql Database?

Second, can I check for NULL with Extbase queries?

I have one column inside my table, with id = 0, and its property
'parent' = NULL.
When I fetch all rows with the property 'parent' = 0, I also get the
row with parent = NULL.

Is it possible to differentiate those two values, or do I need to do
it otherwhise?

Thank you,
David Schreiber