Re: Trouble with NULL

Hi Tom,

thank you for your answer. I know that "x is null" is not "x = null". So how shuld I build my query? The example was simplificated. There are five conditions in the "where" clausule and each of them can be null. If I would have to build my query dynamically it would make no sense to use prepared statement!

Thank you

Hoanui


--- On Mon 05/06, Thomas O'Dowd wrote:
> Hi Hoanui,
>
> = NULL and IS NULL are not the same thing :) Don't you see that you are
> using completely different SQL statements in the java example and in
> the query above it? You should always use the IS NULL version when you
> want to see if something is null, comparing to NULL doesn't work.
>
> Also, the parameterIndex in the PreparedStatement.set() methods below
> should be numbered from 1. 0 is out of range.
>
> Tom.
>
> On Mon, May 06, 2002 at 04:55:55AM -0400, Hoanui Morangie wrote:
> > Hi,
> >
> > could anybody help me please with the following problem: I am using
> Postgres 7.2 on Mandrake Linux 8.2 with JDK 1.4. My table:
> >
> >
> > create table data
> > (
> > id text primary key,
> > ...
> > variant_id text null,
> > ...
> > );
> >
> >
> > Query: select * from data where variant_id is null;
> > works fine - selects one row.
> >
> > In my java code:
> >
> >
> > ...
> > String query = "select * from data where variant_id = ?";
> > ...
> > PreparedStatement pstmt = con.PrepareStatement(query);
> > if (parameter == null)
> > {
> > pstmt.setNull(0, java.sql.Types.VARCHAR);
> > }
> > else
> > {
> > pstmt.setObject(0, parameter);
> > }
> > ...
> >
> >
> > It works if the parameter is not null. If the parameter is null query
> returns no row (should return one). What's wrong?
> >
> > Thank you
> >
> > Hoanui
> >
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