Displaying Null-date in SQL developer

Question

Hi,
I run into the following problem (with SQL developer Vers. 1.2.0 build 2998).
On a table with a date column and a null date in some rows (the default value is "to_date(1, 'J')" ), SQL developer is showing after a query in the SQL worksheet the date "01/01/4713"
However, when I'm executing the same query in SQL*Plus, the columns with a null-date showing the value "01/01/4712"
How is it possible that SQL-Developer and SQL*Plus showing different dates on the same data?
Any suggestion or explanations for this behavior?
Any help is much appreciated.
TIA
Fred

Answer 1

They are both getting the same internal Oracle date format.
They will use different code to translate those bytes into a visible format.
The problem is about year 0 because historically there wasn't one.
The internal date format does permit dates in the year zero, but mostly the SQL interface forbids it.
For example
select to_date('01010000','ddmmyyyy') from dual;
will fail, but
select to_date('01010001','ddmmyyyy')-1 from dual;
will pass
and
select to_char(to_date('01010001','ddmmyyyy')-5,'dd/mon/yyyy') from dual;
produces, well, garbage.
Storing 'dummy' values tends to lead to odd results which is why it is generally frowned upon. Use a null and another column to indicate why a real value isn't appropriate.