Dropdownlist 写省市连级 但是怎么让它第一列显示“请选择..”

<body>
    <form id="form1" runat="server">
    <div>
        <asp:DropDownList ID="ddlProvince" runat="server" AutoPostBack="True" 
            onselectedindexchanged="ddlProvince_SelectedIndexChanged">
        </asp:DropDownList>
        <asp:DropDownList ID="ddlCity" runat="server" AutoPostBack="True" 
            onselectedindexchanged="ddlCity_SelectedIndexChanged">
        </asp:DropDownList>
        <asp:DropDownList ID="ddlDist" runat="server">
        </asp:DropDownList>
    </div>
    </form>
</body>cs代码：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;namespace Ganged
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                Bind();
            }
        }        //数据绑定
        private void Bind()
        {
            using (SqlConnection con = new SqlConnection("server=.;database=ganged;uid=sa;pwd=sa;"))
            {
                con.Open();                //先初始化省                SqlCommand cmdPro = new SqlCommand("select ProID,ProName from T_Province", con);
                SqlDataReader drPro = cmdPro.ExecuteReader();
                this.ddlProvince.DataSource = drPro;
                this.ddlProvince.DataTextField ="ProName";//显示值
                this.ddlProvince.DataValueField = "ProID"; //显示主键
                this.ddlProvince.DataBind();
                drPro.Close();                //初始化市                SqlCommand cmdCity = new SqlCommand("select CityID,CityName from T_City where ProID='" + 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 id,DisName from T_District where CityID='" +this.ddlCity.SelectedValue + "'",con);
                SqlDataReader drDist = cmdDist.ExecuteReader();
                this.ddlDist.DataSource = drDist;
                this.ddlDist.DataTextField = "DisName";
                this.ddlDist.DataValueField = "id";
                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 ProID = this.ddlProvince.SelectedValue;
            using (SqlConnection con = new SqlConnection("server=.;database=ganged;uid=sa;pwd=sa;"))
            {
                con.Open();
                SqlCommand cmdCity = new SqlCommand("select CityID,CityName from T_City where ProID='" + ProID + "'", con);
                SqlDataReader drCity = cmdCity.ExecuteReader();
                this.ddlCity.DataSource = drCity;
                this.ddlCity.DataTextField = "CityName";
                this.ddlCity.DataValueField = "CityID";
                this.ddlCity.DataBind();
                drCity.Close();
                con.Close();
                ddlCityBind();
            }
        }        protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)//DropDownList选中(市改变)产生的事件
        {
            ddlCityBind();
        }        private void ddlCityBind()
        {
            string CityID = this.ddlCity.SelectedValue;
            using (SqlConnection con = new SqlConnection("server=.;database=ganged;uid=sa;pwd=sa;"))
            {
                con.Open();
                SqlCommand cmdDist = new SqlCommand("select id,DisName from T_District where CityID='" + CityID + "'", con);
                SqlDataReader drDist = cmdDist.ExecuteReader();
                this.ddlDist.DataSource = drDist;
                this.ddlDist.DataTextField = "DisName";
                this.ddlDist.DataValueField = "id";
                this.ddlDist.DataBind();
                drDist.Close();
            }
        }
     }
}

解决方案 »

  1.   

    ddl.Items.Insert(0, new ListItem { Text="--请选择--", Value="0" });
      

  2.   

    this.ddlCity.DataSource = drCity;
      this.ddlCity.DataTextField = "CityName";
      this.ddlCity.DataValueField = "CityID";
      this.ddlCity.DataBind();
    this.ddlCity.Items.Insert(0, new ListItem("请选择", ""));drDist.Close();
      

  3.   

    首先在dropdownlist里面添加“请选择”项，然后设置数据源，同时就爱那个AppendDataBoundItems属性设置为true。应该是可以的
      

  4.   

     ListItem list = new ListItem("-请选择-", "0");
                        this.DropDownList1.Items.Insert(0, list); 这样试一下喽 
      

  5.   

    我是这样处理的，循环数据添加入去的
     DropDownList1.Items.Clear();
                    DropDownList1.Items.Add("请选择");
                    for (int i = 0; i <= myds.Tables[0].Rows.Count - 1; i++)
                    {//循环myds的表的省名，添加进DropDownList1
                        DropDownList1.Items.Add(myds.Tables[0].Rows[i]["province"].ToString());
                    }
      

  6.   


    <body>
      <form id="form1" runat="server">
      <div>
      <asp:DropDownList ID="ddlProvince" runat="server" AutoPostBack="True" 
      onselectedindexchanged="ddlProvince_SelectedIndexChanged">
      </asp:DropDownList>
      <asp:DropDownList ID="ddlCity" runat="server" AutoPostBack="True" 
      onselectedindexchanged="ddlCity_SelectedIndexChanged">
      </asp:DropDownList>
      <asp:DropDownList ID="ddlDist" runat="server">
      </asp:DropDownList>
      </div>
      </form>
    </body>cs代码：
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Web;
    using System.Web.UI;
    using System.Web.UI.WebControls;
    using System.Data.SqlClient;namespace Ganged
    {
      public partial class _Default : System.Web.UI.Page
      {
      protected void Page_Load(object sender, EventArgs e)
      {
      if (!IsPostBack)
      {
      Bind();
      }
      }  //数据绑定
      private void Bind()
      {
      using (SqlConnection con = new SqlConnection("server=.;database=ganged;uid=sa;pwd=sa;"))
      {
      con.Open();  //先初始化省  SqlCommand cmdPro = new SqlCommand("select ProID,ProName from T_Province", con);
      SqlDataReader drPro = cmdPro.ExecuteReader();
      this.ddlProvince.DataSource = drPro;
      this.ddlProvince.DataTextField ="ProName";//显示值
      this.ddlProvince.DataValueField = "ProID"; //显示主键
      this.ddlProvince.DataBind();
      this.ddlProvince.Items.Insert(0,"--请选择--");
      drPro.Close();  //初始化市  SqlCommand cmdCity = new SqlCommand("select CityID,CityName from T_City where ProID='" + this.ddlProvince.SelectedValue + "'", con);
      SqlDataReader drCity = cmdCity.ExecuteReader();
      this.ddlCity.DataSource = drCity;
      this.ddlCity.DataTextField = "CityName";
      this.ddlCity.DataValueField = "CityID";
      this.ddlCity.Items.Insert(0,"--请选择--");  
    this.ddlCity.DataBind();
      drCity.Close();  //初始化县  SqlCommand cmdDist = new SqlCommand("select id,DisName from T_District where CityID='" +this.ddlCity.SelectedValue + "'",con);
      SqlDataReader drDist = cmdDist.ExecuteReader();
      this.ddlDist.DataSource = drDist;
      this.ddlDist.DataTextField = "DisName";
      this.ddlDist.DataValueField = "id";
      this.ddlDist.DataBind();
      this.ddlDist.Items.Insert(0,"--请选择--");  
      drDist.Close();
      }  }  protected void ddlProvince_SelectedIndexChanged(object sender, EventArgs e) //DropDownList选中(省改变)产生的事件
      {
      string ProID = this.ddlProvince.SelectedValue;
      using (SqlConnection con = new SqlConnection("server=.;database=ganged;uid=sa;pwd=sa;"))
      {
      con.Open();
      SqlCommand cmdCity = new SqlCommand("select CityID,CityName from T_City where ProID='" + ProID + "'", con);
      SqlDataReader drCity = cmdCity.ExecuteReader();
      this.ddlCity.DataSource = drCity;
      this.ddlCity.DataTextField = "CityName";
      this.ddlCity.DataValueField = "CityID";
      this.ddlCity.DataBind();
      drCity.Close();
      con.Close();
      ddlCityBind();
      }
      }  protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)//DropDownList选中(市改变)产生的事件
      {
      ddlCityBind();
      }  private void ddlCityBind()
      {
      string CityID = this.ddlCity.SelectedValue;
      using (SqlConnection con = new SqlConnection("server=.;database=ganged;uid=sa;pwd=sa;"))
      {
      con.Open();
      SqlCommand cmdDist = new SqlCommand("select id,DisName from T_District where CityID='" + CityID + "'", con);
      SqlDataReader drDist = cmdDist.ExecuteReader();
      this.ddlDist.DataSource = drDist;
      this.ddlDist.DataTextField = "DisName";
      this.ddlDist.DataValueField = "id";
      this.ddlDist.DataBind();
      drDist.Close();
      }
      }
      }
    }
      

  7.   

    我正好也做到一个页面有用这个 this.ddlFengs.DataSource = DBHelper.GetDataSet(sql);
            ddlFengs.DataTextField = "dwmch";
            ddlFengs.DataValueField = "dwbh";
            this.ddlFengs.DataBind();
           this.ddlFengs.Items.Insert(0,"全部");
    直接这样就行了
      

  8.   

     SqlCommand cmdPro = new SqlCommand("select ProID,ProName from T_Province", con);
      SqlDataReader drPro = cmdPro.ExecuteReader();
      this.ddlProvince.DataSource = drPro;
      this.ddlProvince.DataTextField ="ProName";//显示值
      this.ddlProvince.DataValueField = "ProID"; //显示主键
      this.ddlProvince.DataBind();
      this.ddlProvince.Items.Insert(0,"--请选择--");
      drPro.Close();
      

  9.   

     this.ddlCity.DataSource = drCity;
                this.ddlCity.DataTextField = "CityName";
                this.ddlCity.DataValueField = "CityID";
                this.ddlCity.DataBind();
                this.ddlCity.Items.Add(new ListItem("--请选择--", "0"));
                this.ddlCity.SelectedValue = "0";
    这样保证万无一失！
      

  10.   

    this.ddlCity.Items.Insert(0,new ListItem("--请选择--", "0"));这样就可以了呀
      

  11.   

    this.ddlCity.Items.Insert(0,new ListItem("--请选择--", "-1"));
      

  12.   


    this.ddlProvince.Items.Insert(0, new ListItem("请选择...", "请选择..."));
      

  13.   

    this.ddlCity.Items.Insert(0, new ListItem("请选择", ""));
      

  14.   

    绑定之后加this.ddl.Items.Insert(0,"请选择....");
      

  15.   

    this.ddlCity.SelectedIndex=-1;
    把要设默认的哪项索引给-1
    this.ddlCity.Items.Insert(0, new ListItem("请选择", -1));
      

  16.   

    ListItem list = new ListItem("-请选择-", "-1");
    肯定行