java - 从 JComboBox 插入外键

Question

我想从java组合框选定的项目中保存 key ，我做了这个函数，这样我就可以返回表“国籍”的主键并将其作为外键插入其他表中，但它不起作用，它总是返回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

您无法选择表格的所有字段:

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

使用字段名称:

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

也可发送至retrieve data check here但这必须有效

return rs.getInt("nationality_id");