private void Main_Load(object sender, EventArgs e)
        {
            BindComboBox();
        }

        private void BindComboBox()
        {
            DataTable dataTable = new DataTable();
            //组织数据源，这一块需要换成从DB捞取的，就不写了
            dataTable.Columns.Add("ID");
            dataTable.Columns.Add("UsName");
            for (int i = 0; i < 3; i++)
            {
                DataRow newRow = dataTable.NewRow();
                if (i == 0)
                {
                    newRow["ID"] = "1";
                    newRow["UsName"] = "张三";
                }
                else if (i == 1)
                {
                    newRow["ID"] = "2";
                    newRow["UsName"] = "李四";
                }
                else if (i == 2)
                {
                    newRow["ID"] = "3";
                    newRow["UsName"] = "小名";
                }
                dataTable.Rows.Add(newRow);
            }
            dataTable.AcceptChanges();
            //注册事件
            comboBox1.SelectedValueChanged += new EventHandler(comboBox1_SelectedValueChanged);

            //绑定数据源
            comboBox1.DisplayMember = "UsName";
            comboBox1.ValueMember = "ID";
            comboBox1.DataSource = dataTable;
        }

        private void comboBox1_SelectedValueChanged(object sender, EventArgs e)
        {
            if (comboBox1.SelectedValue != null)
                this.textBoxMain.Text = comboBox1.SelectedValue.ToString();
        }