Empty string means "we know its blank" null means "we don't know". When it comes to datatyping, (the whole point of data types in a db), null is its own dataty

Empty string means "we know its blank" null means "we don't know". When it comes to datatyping, (the whole point of data types in a db), null is its own datatype, so forcing the allowance of nulls to get blank strings is kinda stupid and only causes software/application level bugs.