Java and Access

Question

Hi! I have one table "Student" and one "Course". They are connected via a many-to-many relationship.
The database is Access.
In the connecting table I register the grades the student get on a course. This works fine in some cases but not in others.
I get an error message saying something like "Can't add or change the row, it takes an related row in the course table". But I have checked and the row is there.
A funny thing is, that when I added a course in the course table, it was other combinations of student and course that didn't work.
I'll be happy to post my files to anyone who wants to take a look.
This is the error message: (and I also get a .ldb file for locked rows)
java.sql.SQLException: [Microsoft][Drivrutin f�r ODBC Microsoft Access] Du kan inte l�gga till eller �ndra posten. Det kr�vs en relaterad post i tabellen 'Kurs'.
     at sun.jdbc.odbc.JdbcOdbc.createSQLException(JdbcOdbc.java:6958)
     at sun.jdbc.odbc.JdbcOdbc.standardError(JdbcOdbc.java:7115)
     at sun.jdbc.odbc.JdbcOdbc.SQLExecDirect(JdbcOdbc.java:3111)
     at sun.jdbc.odbc.JdbcOdbcStatement.execute(JdbcOdbcStatement.java:338)
     at sun.jdbc.odbc.JdbcOdbcStatement.executeUpdate(JdbcOdbcStatement.java:288)
     at Databashanterare.betygReg(Databashanterare.java:657)
     at BetygReg.actionPerformed(BetygReg.java:389)
     at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1786)
     at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1839)
     at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
     at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
     at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:245)
     at java.awt.Component.processMouseEvent(Component.java:5100)
     at java.awt.Component.processEvent(Component.java:4897)
     at java.awt.Container.processEvent(Container.java:1569)
     at java.awt.Component.dispatchEventImpl(Component.java:3615)
     at java.awt.Container.dispatchEventImpl(Container.java:1627)
     at java.awt.Component.dispatchEvent(Component.java:3477)
     at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3483)
     at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3198)
     at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3128)
     at java.awt.Container.dispatchEventImpl(Container.java:1613)
     at java.awt.Window.dispatchEventImpl(Window.java:1606)
     at java.awt.Component.dispatchEvent(Component.java:3477)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:456)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)

Answer 1

Well, I do have auto increment in "course" and "student" but not in the third table. It can't be? since it depends on what student and what course you choose.
public String sqlInsert(String tabell, String kursNamn, String Litteratur)
          String status = null;
          try
               int idnr = 0;
               int i = 0;
               //int [] temp = new int[100];
               if(kursNamn.equals("") || Litteratur.equals(""))
                    status = "Du m�ste ange b�de kurs och litteratur!";
               if(status == null)
                    skapaKoppling();
                    rs = stmt.executeQuery("select * from " + tabell + " order by Kid");
                    while(rs.next())
                         idnr++; //R�knar ut sista postens idnr.
                         temp[idnr] = rs.getInt("Kid"); // H�r l�ggs alla kvarvarande idnr
                    idnr = temp[idnr]; //Sista postens idnr l�ggs i variabel.
                    System.out.println("idnr: " + idnr);
                    while(i < 20)
                         System.out.println("post "+i+" �r "+temp);
                         i++;
                    idnr++;
                    //int antal = stmt.executeUpdate("insert into Exempel values(1,'Blaha','Mer blaha','2002-02-18 19:23:21',"+true+")");
                    int antal = stmt.executeUpdate("insert into "+tabell+" values("+idnr+",'"+kursNamn+"','"+Litteratur+"')");
                    System.out.println("Antal rader som ber�rdes: " + antal);
                    status = "Kurs registrerad!";
                    avslutaKoppling();
               }//End if
          catch(SQLException sqle)
               sqle.printStackTrace();
          return status;
     }//End metod SQLinsert
public String sqlInsert2(String tabell, String studentNamn)
          String status = null;
          try
               int idnr = 0;
               int i = 0;
               int [] temp = new int[100];
               if(studentNamn.equals(""))
                    status = "Du m�ste ange student!";
               if(status == null)
                    skapaKoppling();
                    rs = stmt.executeQuery("select * from " + tabell + " order by Sid");
                    while(rs.next())
                         idnr++; //R�knar ut sista postens idnr.
                         temp[idnr] = rs.getInt("Sid"); // H�r l�ggs alla kvarvarande idnr
                    idnr = temp[idnr]; //Sista postens idnr l�ggs i variabel.
                    System.out.println("idnr: " + idnr);
                    //Test
                    while(i < 20)
                         i++;
                         System.out.println("post "+i+" �r "+temp[i]);
                    idnr++; //S�tter idnr till nummer efter sista post.
                    //int antal = stmt.executeUpdate("insert into Exempel values(1,'Blaha','Mer blaha','2002-02-18 19:23:21',"+true+")");
                    int antal = stmt.executeUpdate("insert into "+tabell+" values("+idnr+",'"+studentNamn+"')");
                    System.out.println("Antal rader som ber�rdes: " + antal);
                    status = "Student registrerad!";
                    avslutaKoppling();
               }//End if
          catch(SQLException sqle)
               sqle.printStackTrace();
          return status;
     }//End metod SQLinsert 2