The issue is that some databases support the comparison of
x = NULL
This is not a feature AFAIK that is an ANSI requirement.
You need to use IS NULL in your query.
you can use setNull or pass a null to setXXX if you choose, but this
does not correct your SQL grammer, you need to provide the correct SQL
grammer for the given backend end that you are using for handling NULLs.
Marieke Vandamme wrote:
Hello,
When using other Database Drivers (like postgres)
this is supported.
When suggesting Derby doesn't, what are the
alternatives
for my problem?
I really need to use it in the form of
PreparedStatement,
like "select * from table where value = ?",
because we are using select statement with more
than
6 parameter-values.
In what ways is the setNull function usefull ?
When trying to solve my problem, in many examples
I found :
if (value == null)
ps.setNull(1,
Types.VARCHAR);
else
ps.setString(1,
value);
Thanks !
-------
Marieke Vandamme <[EMAIL PROTECTED]>
writes:
> Hello,
>
> We are trying to perform a select query to the Derby database with
> PreparedStatement
>
> PreparedStatement ps = c.prepareStatement("select * from table
where value
> = ?");
> //several methods performed on statement (separately ofcourse)
> 1. ps.setNull(1,Types.VARCHAR);
> 2. ps.setObject(1, null, Types.VARCHAR);
> 3. ps.setString(1, null) ;
>
> The table contains null values, but the resultset is empty for the
3
> cases.
It doesn't return any rows because "value = null" does not evaluate
to
true even when value in fact is null, in which case it evaluates to
unknown. "value is null" should work.
--
Knut Anders
|
- Re: setNull in select doesn't work Lance J. Andersen
-
