Re: java.lang.NullPointerException on imbricated queries

Olivier,

One statement can, by default, have only one result set, when you execute the
second query the first result set is closed.

You'll need to rewrite your code to something like:

Statement innerStmt = conn.createStatement();

Query1 = "SELECT * FROM example1;";
rs1 = stmt.executeQuery(Query1);
while (rs1.next()) {
Query2 = "SELECT * FROM example2;
rs2 = innerStmt.executeQuery(Query2);
while (rs2.next()) {
// Something .../...
}
}

The postgresql jdbc driver probably shouldn't npe in these cases,

Hope this helps,

Michael

Olivier BULLAT wrote:
> Hello,
>
> We have a web application in Apache, Posgresql 7.2, servlet java (JDK
> 1.2), Jserv and jdbc7.2dev-1.2.jar.
> A lot of programs runs normally with JDBC access to postgresql. But when
> we use two imbricated queries like this example, a message
> JAVALANGEXEPTION java.lang.NullPointerException occurs:
>
> 1 Query1 = "SELECT * FROM example1;";
> 2 rs1 = stmt.executeQuery(Query1);
> 3 while (rs1.next()) {
> 4 Query2 = "SELECT * FROM example2;
> 5 rs2 = stmt.executeQuery(Query2);
> 6 while (rs2.next()) {
> 7 // Something .../...
> 8 }
> 9 }
>
> Programme DetailsRapports.java: JAVALANGEXEPTION
> java.lang.NullPointerException:
> java.lang.NullPointerException:
> at org.postgresql.jdbc2.ResultSet.next(ResultSet.java:113)
> at DetailsRapports.AfficheEntrees(DetailsRapports.java:68)
> at DetailsRapports.service(DetailsRapports.java:43)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:588)
> at
> org.apache.jserv.JServConnection.processRequest(JServConnection.java:317)
> at org.apache.jserv.JServConnection.run(JServConnection.java:188)
> at java.lang.Thread.run(Thread.java:479)
>
> This message occurs on line 3 "while (rs1.next()) {" after a first good
> Query1 and a first good Query2.
>
> Any help would be appreciated.
>
>
> --------------------------------------------------------------------------
> Olivier BULLAT
> Responsable du Centre de Ressources Informatiques
> Institut Francais de Mecanique Avancee - IFMA
> Campus de CLERMONT-FERRAND / Les Cezeaux
> BP 265
> 63175 AUBIERE Cedex
> Tel: 04.73.28.80.35
> Fax: 04.73.28.81.00
> mail: _Olivier(dot)Bullat(at)ifma(dot)fr
> http://www.ifma.fr <http://www.ifma.fr/>
> _--------------------------------------------------------------------------
>

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