insert foreign key from JComboBox

Question

I want to save the key from a java combobox selected item i made this function so i could return the primery key of table "nationality" and insert it as foreign key in other tables but it doesn't work it return always 0:

public int getNat() throws Exception{
    String query = "SELECT code_nat FROM nationality WHERE nationality=?";
       try ( PreparedStatement stat = cnx.prepareStatement(query) ) {

          stat.setString(1, (String)cmbNat.getSelectedItem());
          rslt = stat.executeQuery();
          return rslt.getInt(1);

       }catch(SQLException ex){
              ex.printStackTrace();
              return 0; 
       }
}

Answer 1

you cannot select all fields of the table:

String query = "SELECT * FROM nationality WHERE nationality=?";
//                     ↑ here

Use the field name instead:

String query = "SELECT nationality_id FROM nationality WHERE nationality=?";

Also to retrieve data check here but this must work

return rs.getInt("nationality_id");

Answer 2

the insertion function

public void insertInfo() throws Exception{
    try{
        int codeNat = getNat();

        String query = "INSERT INTO info (id,name,code_nat) VALUES (?,?,?)";

        stat = cnx.prepareStatement(query);
        stat.setString(1, txtId.getText());
        stat.setString(2, txtName.getText());
        stat.setInt(3, codeNat);

        stat.execute();
        Update_table();

    }catch(SQLException ex){
        JOptionPane.showMessageDialog(null,ex);
    }
    finally{
        try{
            stat.close();
            cnx.close();
        }catch(Exception e){

        }
    }
}