in reply to
Re: "undef" is not NULL and what to do about it
in thread "undef" is not NULL and what to do about it
All fields should have (default) values.
So how do you represent unknown values? By using a default "UNKNOWN"?
Then I might just as well use a NULL...
If I insert an empty string into a varchar field in Oracle, it helpfully inserts a NULL instead.
VARCHAR-fields do in theory exist in Oracle but nobody uses them.
You are talking about VARCHAR2-fields and for them an empty string IS a NULL. There is no difference at all. If you use that data-type you must be aware of this.