DropDownList 和Combox 数据绑定的常用方法

web       DropDownList绑定数据源的几种方式
 第一种
                this.ddltype.DataTextField = "btName";//显示的值
                this.ddltype.DataValueField = "btId";//获取dropdownlist中的值
                ddltype.DataSource = service.GetBusinessTypeAll("");
                this.ddltype.DataBind();
第二种
                 DataTable dt_GetBusinessName = service.GetBusinessTypeAll("");

                //表中无数据的话直接返回
                if (dt_GetBusinessName == null)
                    return;

                for (int i = 0; i < dt_GetBusinessName.Rows.Count; i++)
                {
                    ddltype.Items.Add(new ListItem(dt_GetBusinessName.Rows[i]["btName"].ToString().Trim(),//显示的值
                    dt_GetBusinessName.Rows[i]["btId"].ToString().Trim()));
                }s
                ddltype.Items.Add(new ListItem("全部", "-1"));
                ddltype.Text = "全部";

如何选中DropDownList1中的值用

  protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.TextBox1.Text = this.DropDownList1.SelectedItem.Text.ToString();
    }

windows     combox的手写数据绑定
            第一种：
                cCombox1.DisplayMember = "btName";//显示的值
                cCombox1.ValueMember = "btId";
                cCombox1.DataSource = _manageService.GetBusinessTypeAll(this.UserInfo.uNote1);
            第二种：
                 DataTable dt_GetStateByName = _financeService.GetStateByNam(UserInfo.uNote1);

                //表中无数据的话直接返回
                if (dt_GetStateByName == null)
                    return;

                for (int i = 0; i < dt_GetStateByName.Rows.Count; i++)
                {
                       cbType2.Items.Add(new ListItem(dt_GetStateByName.Rows[i]["osState"].Trim(),
                       dt_GetStateByName.Rows[i]["osName"].ToString().Trim()));//显示的值
                }
                cbType2.Items.Add(new ListItem("-1", "全部"));
                cbType2.Text = "全部";