java add items to JcomboBox from Database

How can I add items to combobox from Access database?

My code:

    String sql = "SELECT * FROM Owner,Cars "
        + "WHERE carID=CarID_ "
        + "ORDER BY OwnerName;";
    ResultSet dane = zadanie.executeQuery(sql);
    while (dane.next())
    {
        comboBox_2.addItem(new(dane.getString("year")));
    }
    zadanie.close();
} catch(SQLException sqe) {
    System.out.println("SQl error");
}

but it throws "Sql error" btw this code:

    String sql="SELECT * FROM Cars ;";
    ResultSet dane = zadanie.executeQuery(sql);
    while (dane.next())
    {       

        System.out.println(
                dane.getString("CarName")+"\t" +
                dane.getString("year"));

    }
    zadanie.close();
} catch(SQLException sqe) {
    System.out.println("SQl error");
}

works perfectl开发者_如何转开发y but if write in that way it shows error

 comboBox_2.addItem(new String(dane.getString("CarName"))); 
        System.out.println(
                dane.getString("CarName")+"\t" +
                dane.getString("year"));

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If you're in a thread other than the EDT, it is essential to ensure that an event that modifies a Swing component is posted on the EDT. The utility class SwingUtilities allows you to do such.

SwingUtilities.invokeLater(new Runnable(){
    @Override
    public void run(){
        comboBox_2.addItem(new(dane.getString("year")));
    }
});

But this is not your current problem. Instead of printing out that useless message (i.e. SQL error), why not print a stack trace? Also, I suggest you read up on SQLException.

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You do have an error in your SQL at WHERE carID = CarID_" You are missing the actual ID of the Car. Hope this helps!

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It looks like its a problem with your SQL... does that statement execute correctly outside of Java?

SELECT * FROM owner JOIN cars USING (carID) ORDER BY OwnerName;

May work out better for you?