您需要将要显示在下拉菜单中的选项放入数组中，就像这样

You need to put the options you want displayed in the drop down into an array, like so

$options = array(
  'red'   => 'Red',
  'green' => 'Green',
  'blue'  => 'Blue',
);

// The params here are:
// 'color'    => name of the drop down
// '$options' => options for the drop down
// 'red'      => the selected value of the drop down
echo form_dropdown('color', $options, 'red');

我要做的是在模型中创建一个函数，例如 $ model -> dropdown_options（）并使用它从数据库中获取行并将其放入数组中。

What I would do is create a function in my model, say $model->dropdown_options() and use that to get the rows from the database and put them into an array.