省市区三级如何设置初始值

#region 实现省市区三级
    //数据绑定
    private void BindPro()
    {
        using (SqlConnection con = new SqlConnection("server=.;database=lskj;uid=sa;pwd=sa"))
        {
            con.Open();

            //初始化省

            SqlCommand cmdPro = new SqlCommand("select ProvinceID,ProvinceName from S_Province", con);
            SqlDataReader drPro = cmdPro.ExecuteReader();
            this.ddlProvince.DataSource = drPro;
            this.ddlProvince.DataTextField = "ProvinceName";
            this.ddlProvince.DataValueField = "ProvinceID";
            this.ddlProvince.DataBind();
            drPro.Close();

            //初始化市

            SqlCommand cmdCity = new SqlCommand("select CityID,CityName from S_City where ProvinceID = " + this.ddlProvince.SelectedValue + "", con);
            SqlDataReader drCity = cmdCity.ExecuteReader();
            this.ddlCity.DataSource = drCity;
            this.ddlCity.DataTextField = "CityName";
            this.ddlCity.DataValueField = "CityID";
            this.ddlCity.DataBind();
            drCity.Close();
            //初始化县

            SqlCommand cmdDist = new SqlCommand("select DistrictID,DistrictName from S_District where DistrictID = " + this.ddlCity.SelectedValue + "", con);
            SqlDataReader drDist = cmdDist.ExecuteReader();
            this.ddlDist.DataSource = drDist;
            this.ddlDist.DataTextField = "DistrictName";
            this.ddlDist.DataValueField = "DistrictID";
            this.ddlDist.DataBind();
            drDist.Close();
        }
    }

    protected void ddlProvince_SelectedIndexChanged(object sender, EventArgs e) //DropDownList选中（省改变）产生的事件
    {
        string ProvinceID = this.ddlProvince.SelectedValue;
        using (SqlConnection con = new SqlConnection("server=.;database=lskj;uid=sa;pwd=sa;"))
        {
            con.Open();
            SqlCommand cmdCity = new SqlCommand("select CityID,CityName from S_City where ProvinceID=" + ProvinceID + "", con);
            SqlDataReader drCity = cmdCity.ExecuteReader();
            this.ddlCity.DataSource = drCity;
            this.ddlCity.DataTextField = "CityName";
            this.ddlCity.DataValueField = "CityID";
            this.ddlCity.DataBind();
            this.ddlCity.Items.Insert(0,"-请选择-");
            this.ddlCity.Items[0].Value = "0";
            drCity.Close();
            con.Close();
            ddlCityBind();
        }

    }
    protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)
    {
        ddlCityBind();
    }

    private void ddlCityBind()
    {
        string CityID = this.ddlCity.SelectedValue;
        using (SqlConnection con = new SqlConnection("server=.;database=lskj;uid=sa;pwd=sa;"))
        {
            con.Open();
            SqlCommand cmdDist = new SqlCommand("select DistrictID,DistrictName from S_District where CityID =" + CityID + "", con);
            SqlDataReader drDist = cmdDist.ExecuteReader();
            this.ddlDist.DataSource = drDist;
            this.ddlDist.DataTextField = "DistrictName";
            this.ddlDist.DataValueField = "DistrictID";
            this.ddlDist.DataBind();
            this.ddlDist.Items.Insert(0, "-请选择-");
            this.ddlDist.Items[0].Value = "0";
            drDist.Close();
        }
    }
    #endregion

请问如何在页面的省市区里都显示“-请选择-” --------------------编程问答-------------------- 兄弟也可以用这个办法试试看
 ListItem a = new ListItem("==请选择==", "0");
 drp_user_Distribution.Items.Add(a);
drp_user_Distribution.SelectedIndex = 0;
 if (ds != null && ds.Tables[0].Rows.Count != 0)
                {
                    for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
                    {
                        ListItem item = new ListItem(ds.Tables[0].Rows[i]["username"].ToString(), ds.Tables[0].Rows[i]["Id"].ToString());
                        drp_user_Distribution.Items.Add(item);
                        drp_usersearch.Items.Add(item);
                        drp_user_Release.Items.Add(item);
                    }
                }

补充：.NET技术 ,  C#