Hello,
I'm curious to know how NULLs are stored into a database ?
It surely depends on the database server but I would like to have an general idea about it.
First try:
Suppose that the server put a undefined value (could be anything) into the field for a NULL value.
Could you be very lucky and retrieve the NULL value with
...WHERE field = 'the undefined value (remember, could be anything...)'
Second try:
Does the server have a flag or any meta-data somewhere to indicate this field is NULL ?
Then the server must read this meta data to verify the field.
If the meta-data indicates a NULL value and if the query doesn't have "field IS NULL", then the record is ignored.
It seems too easy...