"ORA-01405" returned with .NET driver on Oracle server 9.2

Hi.
I am developing a web application (with ASP.NET, framework version 1.1) which has to run some queries on a Oracle server (version 9.2), through System.Data.OracleClient.OracleDataAdapter.

When I run a particular query, I retreive the following error through the .NET driver
"ORA-01405: fetched column value is NULL".

The SQL query that raises the problem is something like that
"SELECT [...],

RIGHE_OFF.IS_CANONE As Canone,
[...]"

Moreover, if I run the same query with TOAD (sql client for Oracle), no exception is raisen, even if some NULL data is effectively returned.

After several hours wihtout any idea, I found a "dirty" solution to fix the problem, and now my query is
"SELECT [...],

CASE WHEN RIGHE_OFF.IS_CANONE IS NULL THEN         NULL
ELSE
        RIGHE_OFF.IS_CANONE
END As Canone,
[...]"

The query finally returns what I need, but my solution is just a workaround on the problem, because, even looking for informations on the net, I coudn't understand the problem. And, above all, I don't understand why, with such a fool artifice, I could solve the problem!

Can someone tell me how to avoid that stupid trick, or at least why I have to do it?
Thanx in advance!
Alessio Received on Thu Nov 09 2006 - 10:41:12 CST