Re: toString() problem

[maarten <ma...@dns.be>]

Radu Preotiuc-Pietro wrote:

>XMLSchema, as databases, makes a distiction between values "not present" and values "present, but set to null" that Java doesn't make (in addition to the distinction between "null" and "empty").
>  
>
Radu, I don't quite follow what you mean with "as databases"
What difference does a database make between "values not present" and 
"values present but set to null" ?
I always thought that setting a value to null is saying "the value is 
not present" ?

create table tab (a number, b varchar(10));
// value no present
insert into tab (a)    values (1);
// value set to null
insert into tab (a,b) values (1, null);  

How can I make distinction between these two rows ?

On a sidenote:  Oracle doesn't even make distinction between empty 
string and null, don't know about other databases though.

Maarten

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