Re: Handling null values in char fields from JDBC

Paulo -
Thanks for all your help ..
This is exactly what I am looking for.

Sean -

-----Original Message-----
From: "Paulo Merson" <paulo@summa-tech.com>
Date: Tue, 22 Jan 2002 14:11:38 -0500
To:  <pgsql-jdbc@postgresql.org>
Subject: Re: [JDBC] Handling null values in char fields from JDBC


> You should use wasNull after each getXxx method if the column being read
> allows null. It's as simple as:
>
>       text = rs.getString(2);
>     if (rs.wasNull()) {
>         System.out.println("This column is SQL null");
>     } else {
>         // process data
>     }
>
> It's particularly useful when you are reading values to basic data type
> variables (not objects) because there is no value that uniquely
> represents the SQL null. For example getInt returns 0 (zero) if the
> value is null but it would also return 0 when the value is zero.
> (ResultSet.getString must return null when the column value is null; I'm
> using it in Posrgres JDBC driver and it works fine.)
>
> Check
> http://java.sun.com/j2se/1.4/docs/api/java/sql/ResultSet.html#wasNull()
>
> Paulo Merson
> Summa Technologies - www.summa-tech.com
>
>
> -----Original Message-----
> From: pgsql-jdbc-owner@postgresql.org
> [mailto:pgsql-jdbc-owner@postgresql.org] On Behalf Of Sean Duffy
> Sent: Tuesday, January 22, 2002 1:34 PM
> To: Paulo Merson; pgsql-jdbc@postgresql.org
> Subject: Re: [JDBC] Handling null values in char fields from JDBC
>
>
>
> -----Original Message-----
> From: "Paulo Merson" <paulo@summa-tech.com>
> Date: Tue, 22 Jan 2002 09:46:44 -0500
> To:  <pgsql-jdbc@postgresql.org>
> Subject: Re: [JDBC] Handling null values in char fields from JDBC
>
> Paulo -
>
> I am using ResultSet.getString but Im not
> sure how I can use ResultSet.wasNull.  Is
> there an example I could look at?
>
> Thanks :)
>
> Sean -
>
> > Are you using ResultSet.getString and then ResultSet.wasNull?
> >
> > Paulo Merson
> > Summa Technologies - www.summa-tech.com
> >
> > -----Original Message-----
> > From: pgsql-jdbc-owner@postgresql.org
> > [mailto:pgsql-jdbc-owner@postgresql.org] On Behalf Of Sean Duffy
> > Sent: Tuesday, January 22, 2002 9:22 AM
> > To: pgsql-jdbc@postgresql.org
> > Subject: [JDBC] Handling null values in char fields from JDBC
> >
> >
> >
> > I am running Postgresql 7.1.3 and using the 7.1-1.2 jar jdbc driver.
> I
> > noticed that when I used a ResultSet.getString("charfield") call to
> > fetch null data from the char field I get a null pointer exception
> > error.  My question is two fold..
> > 1) Is this normal behavior for the jdbc driver?
> > 2) Is there a recommended way of trapping for a null value in a char
> > field (besides just going into the db with psql and setting all null
> > values to '')?
> >
> > I have looked thru two different Postgresql manuals but have not been
> > able to find anything referring to null value handling at the jdbc
> > level.
> >
> > If anyone can pt me in the right direction I
> > would really appreciate it.
> >
> > Thanks!
> > --
> >
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