Question

I am trying to add a username into a .accdb local database. My code is as followed:

try
    {
        String sql = "INSERT INTO Users VALUES('?');";
        System.out.println("SQL : " + sql);

        System.out.println("USER : " + user);

        PreparedStatement stmt = database.prepareStatement(sql);
        System.out.println("Statement : " + stmt);
        stmt.setString(1, user); 
        System.out.println("Statement : " + stmt);

        ResultSet results = stmt.executeQuery(); 
        System.out.println("Results : " + results);
    }
    catch(SQLException sqlEx)
    {
        System.out.println("* Cannot execute insertion! *");
        sqlEx.printStackTrace();
        System.exit(1);
    }

The console output is :

SQL : INSERT INTO Users VALUES('?');
USER : TEST
Statement : sun.jdbc.odbc.JdbcOdbcPreparedStatement@1bf73fa
Exception in thread "Thread-0" java.lang.NullPointerException
at sun.jdbc.odbc.JdbcOdbcPreparedStatement.clearParameter    (JdbcOdbcPreparedStatement.java:1023)
at sun.jdbc.odbc.JdbcOdbcPreparedStatement.setChar    (JdbcOdbcPreparedStatement.java:3057)
at sun.jdbc.odbc.JdbcOdbcPreparedStatement.setString    (JdbcOdbcPreparedStatement.java:766)
at MultiEchoServer.addRegisteredUser(MultiEchoServer.java:100)
at ClientHandler.run(MultiEchoServer.java:339)

Thanks for your help!

Answer 1

This is the problem, I suspect:

String sql = "INSERT INTO Users VALUES('?');";

That statement doesn’t have any parameters – it will always insert a question mark, because you’ve got it in quotes so it’s a value rather than a parameter. I think you want:

String sql = "INSERT INTO Users VALUES(?)";

(Note that I’ve removed the extra semi-colon at the end of the SQL statement too – I don’t believe you really want that.)

It’s unfortunate that the exception isn’t more helpful, admittedly… I’d expect something to indicate that index 1 was out of range.