Error execute query from stateful session bean

Question

Hi,
I created a stateful session bean, it's flow are as following:
- client invoke open()
- client "iterate" using method next()
- client invoke close()
In open, I get Connection to db-source, create a PreparedStatement, and execeute the query, store in a resultset.
In next(), I traverse the resultSet using next().
In close(), I close both resultset, statemtn, and connection.
Here's the snippet of my code:public SynchCatalogBean implements SessionBean {
    private Connection conn;
    private PreparedStatement stmt;
    private ResultSet rs;
    private static final String = "SELECT ? FROM ?";
    public void openCategory() throws RemoteException {
        DataSource dataSource =
            (DataSource)jndiContext.lookup(DATASOURCE);
        con = dataSource.getConnection();
        stmt = con.prepareStatement(QUERY);
        stmt.setString(1, "id");
        stmt.setString(2, "category");
        rs = stmt.executeQuery(); //this throws exception
    public String next() throws ... {
        if (rs.next())
    public void close() throws ... {
        rs.close();
        stmt.close();
        conn.close();
}Well, the problem is, once I test with a simple client, the line rs = stmt.executeQuery() produce exception like this:[SynchCatalog] TRANSACTION ROLLBACK EXCEPTION:Error opening category; nested exception is:
    java.rmi.RemoteException: Error opening category
[SynchCatalog] java.rmi.RemoteException: Error opening category
[SynchCatalog]  at matashop.product.ejb.SynchCatalogBean.openCategory(SynchCatalogBean.java:66)
[SynchCatalog]  at java.lang.reflect.Method.invoke(Native Method)
[SynchCatalog]  at org.jboss.ejb.StatefulSessionContainer$ContainerInterceptor.invoke(StatefulSessionContainer.java:570)
[SynchCatalog]  at org.jboss.ejb.plugins.SecurityInterceptor.invoke(SecurityInterceptor.java:190)
[SynchCatalog]  at org.jboss.ejb.plugins.StatefulSessionInstanceInterceptor.invoke(StatefulSessionInstanceInterceptor.java:209)
[SynchCatalog]  at org.jboss.ejb.plugins.TxInterceptorCMT.invokeNext(TxInterceptorCMT.java:133)
[SynchCatalog]  at org.jboss.ejb.plugins.TxInterceptorCMT.runWithTransactions(TxInterceptorCMT.java:263)
[SynchCatalog]  at org.jboss.ejb.plugins.TxInterceptorCMT.invoke(TxInterceptorCMT.java:99)
[SynchCatalog]  at org.jboss.ejb.plugins.LogInterceptor.invoke(LogInterceptor.java:195)
[SynchCatalog]  at org.jboss.ejb.StatefulSessionContainer.invoke(StatefulSessionContainer.java:326)
[SynchCatalog]  at org.jboss.ejb.plugins.jrmp.server.JRMPContainerInvoker.invoke(JRMPContainerInvoker.java:392)
...My stateful-bean is "read-only" bean, it just execute a select statement, so why Jboss complain about transaction exception? Can anyone help me?
-- Verdi March --

Answer 1

agree, you cannot pass tablenames as ? parameters. Instead you should generate your SQL statement dynamically
private static final String = "SELECT ? FROM ";
public void openCategory() throws RemoteException {
stmt = con.prepareStatement(QUERY + "category");
stmt.setString(1, "id");