Why does Oracle 9i treat an empty string as NULL?

Question

I know that it does consider \' \' as NULL, but that doesn\'t do much to tell me why this is the case. As I understand the SQL specifications

Answer 1

First of all, null and null string were not always treated as the same by Oracle. A null string is, by definition, a string containing no characters. This is not at all the same as a null. NULL is, by definition, the absence of data.

Five or six years or so ago, null string was treated differently from null by Oracle. While, like null, null string was equal to everything and different from everything (which I think is fine for null, but totally WRONG for null string), at least length(null string) would return 0, as it should since null string is a string of zero length.

Currently in Oracle, length(null) returns null which I guess is O.K., but length(null string) also returns null which is totally WRONG.

I do not understand why they decided to start treating these 2 distinct "values" the same. They mean different things and the programmer should have the capability of acting on each in different ways. The fact that they have changed their methodology tells me that they really don't have a clue as to how these values should be treated.