using (SqlConnection con = new SqlConnection(insertClass.dbPath))
{
    con.Open();
    using (SqlDataAdapter sda = new SqlDataAdapter(
    "SELECT CategoryID, Category FROM Category WHERE Status='Active' ", con))
    {
        //Fill the DataTable with records from Table.
        DataTable dt = new DataTable();
        sda.Fill(dt);
        //Insert the Default Item to DataTable.
        DataRow row = dt.NewRow();
        row[0] = 0;
        row[1] = "(Selecione)";
        dt.Rows.InsertAt(row, 0);
        //Assign DataTable as DataSource.
        cboProductTypeName.DataSource = dt;
        cboProductTypeName.DisplayMember = "Category";
        cboProductTypeName.ValueMember = "CategoryID";
    }
}             
con.Close();

你可以像这样使用匿名类:

comboBox.DisplayMember = "Text";
comboBox.ValueMember = "Value";

comboBox.Items.Add(new { Text = "report A", Value = "reportA" });
comboBox.Items.Add(new { Text = "report B", Value = "reportB" });
comboBox.Items.Add(new { Text = "report C", Value = "reportC" });
comboBox.Items.Add(new { Text = "report D", Value = "reportD" });
comboBox.Items.Add(new { Text = "report E", Value = "reportE" });

更新:虽然上面的代码将正确显示在组合框中，你将不能使用组合框的SelectedValue或SelectedText属性。为了能够使用这些，绑定组合框如下:

comboBox.DisplayMember = "Text";
comboBox.ValueMember = "Value";

var items = new[] { 
    new { Text = "report A", Value = "reportA" }, 
    new { Text = "report B", Value = "reportB" }, 
    new { Text = "report C", Value = "reportC" },
    new { Text = "report D", Value = "reportD" },
    new { Text = "report E", Value = "reportE" }
};

comboBox.DataSource = items;

一个使用DataTable的例子:

DataTable dtblDataSource = new DataTable();
dtblDataSource.Columns.Add("DisplayMember");
dtblDataSource.Columns.Add("ValueMember");
dtblDataSource.Columns.Add("AdditionalInfo");

dtblDataSource.Rows.Add("Item 1", 1, "something useful 1");
dtblDataSource.Rows.Add("Item 2", 2, "something useful 2");
dtblDataSource.Rows.Add("Item 3", 3, "something useful 3");

combo1.Items.Clear();
combo1.DataSource = dtblDataSource;
combo1.DisplayMember = "DisplayMember";
combo1.ValueMember = "ValueMember";

   //Get additional info
   foreach (DataRowView drv in combo1.Items)
   {
         string strAdditionalInfo = drv["AdditionalInfo"].ToString();
   }

   //Get additional info for selected item
    string strAdditionalInfo = (combo1.SelectedItem as DataRowView)["AdditionalInfo"].ToString();

   //Get selected value
   string strSelectedValue = combo1.SelectedValue.ToString();

不知道这是否适用于原始帖子中给出的情况(不要介意这是两年后的事实)，但这个例子对我来说是适用的:

Hashtable htImageTypes = new Hashtable();
htImageTypes.Add("JPEG", "*.jpg");
htImageTypes.Add("GIF", "*.gif");
htImageTypes.Add("BMP", "*.bmp");

foreach (DictionaryEntry ImageType in htImageTypes)
{
    cmbImageType.Items.Add(ImageType);
}
cmbImageType.DisplayMember = "key";
cmbImageType.ValueMember = "value";

要读取回值，必须将SelectedItem属性转换为DictionaryEntry对象，然后可以计算该对象的Key和value属性。例如:

DictionaryEntry deImgType = (DictionaryEntry)cmbImageType.SelectedItem;
MessageBox.Show(deImgType.Key + ": " + deImgType.Value);

您必须创建自己的类类型并重写ToString()方法以返回所需的文本。下面是一个你可以使用的类的简单例子:

public class ComboboxItem
{
    public string Text { get; set; }
    public object Value { get; set; }

    public override string ToString()
    {
        return Text;
    }
}

下面是它使用的一个简单例子:

private void Test()
{
    ComboboxItem item = new ComboboxItem();
    item.Text = "Item text1";
    item.Value = 12;

    comboBox1.Items.Add(item);

    comboBox1.SelectedIndex = 0;

    MessageBox.Show((comboBox1.SelectedItem as ComboboxItem).Value.ToString());
}

您应该在运行时使用动态对象来解析组合框项。

comboBox.DisplayMember = "Text";
comboBox.ValueMember = "Value";

comboBox.Items.Add(new { Text = "Text", Value = "Value" });

(comboBox.SelectedItem as dynamic).Value