DropDownList默认值问题，谢了

前台：
<asp:DropDownList ID="ddlRateName" runat="server" Style="font-size: 11px; color: blue"
                                        DataSource = '<%# BindRateName() %>' DataTextField = "rateName" SelectedValue='<%# Bind("rateName") %>'>
                                    </asp:DropDownList>后台：
#region 绑定职称
    protected DataTableReader BindRateName()
    {
        string selectSql = "select distinct rateName from zd_employee where rateName is not null and rateName != '' order by rateName ";
        SqlData da = new SqlData();
        DataTableReader dr = null;        try
        {
            dr = da.ExceDr(selectSql);
        }
        catch
        {
            Response.Write("<script>alert('绑定职称信息失败!')</script>");
            return null;
        }        return dr;
    }
    #endregion

绑定DropDownList的时候可以绑定一个是显示值一个是value
DropDownList1.DataTextField="aa"//显示的值
DropDownList1.DataValueField="bb"隐藏的值,取的时候就用DropDownList1.SelectedValue
这样就可以取到bb的值了

DropDownList有一个selected 属性，判断b的值是否等于1，然后取出相应的a值，然后赋值

SelectedValue 是这个属性，刚才说错了

this.DropDownList1.DataSource = dataTable;
this.DropDownList1.DataTextField = "aa";
this.DropDownList1.DataValueField = "bb";
this.DropDownList1.DataBind();
this.DropDownList1.SelectedValue = "1";

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;namespace WebApplication1
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                InitData();
            }
        }        private void InitData()
        {
            DataTable table = GenerateDataTable();
            this.DropDownList1.DataSource = table;
            this.DropDownList1.DataTextField = "aa";
            this.DropDownList1.DataValueField = "bb";
            this.DropDownList1.DataBind();
        }        /// <summary>
        /// 产生DataTable
        /// </summary>
        /// <returns></returns>
        private DataTable GenerateDataTable()
        {
            DataTable table = new DataTable();
            DataColumn aa = new DataColumn("aa", typeof(string));
            DataColumn bb = new DataColumn("bb", typeof(int));
            table.Columns.Add(aa);
            table.Columns.Add(bb);            DataRow row = table.NewRow();
            row["aa"] = "f1";
            row["bb"] = 0;
            table.Rows.Add(row);            row = table.NewRow();
            row["aa"] = "f2";
            row["bb"] = 0;
            table.Rows.Add(row);            row = table.NewRow();
            row["aa"] = "f3";
            row["bb"] = 1;
            table.Rows.Add(row);            row = table.NewRow();
            row["aa"] = "f4";
            row["bb"] = 0;
            table.Rows.Add(row);            return table;
        }        protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
        {            Response.Write(string.Format("您选择的值是：{0}", DropDownList1.SelectedValue));
        }
    }
}<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication1._Default" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>无标题页</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged ="DropDownList1_SelectedIndexChanged">
        </asp:DropDownList>
    </div>
    </form>
</body>
</html>

在加载数据或者绑定后添加这一句
DropDownList1.Items.Insert(0, "F3");

1. 如果自己写数据绑定方法：
         //绑定年
         public static void BindYear(DropDownList list)
        {            list.Items.Clear();
            ListItem item = new ListItem("2010");
            list.Items.Insert(0, item);
            item = new ListItem("2009");
            list.Items.Insert(1, item);
            item = new ListItem("2008");
            list.Items.Insert(2, item);
        }2.如果查询数据库数据绑定方法：
        //绑定部门下拉框
        public static void BindDept(DropDownList list)
        {
            DataSet ds = new DataSet();
            ds = 你的查询方法
            list.DataSource = ds;
            list.DataTextField = "deptname";
            list.DataValueField = "deptcode";
            list.DataBind();        }

设下拉列表的datatextfield这是给用户看的,datavaluefield是点击时它对应的值

谢谢大家了可我要是当bb=1时DropDownList默认值显示的是F3谢谢

DataTable table = 你获取数据的集合表
            this.DropDownList1.DataSource = table;
            this.DropDownList1.DataTextField = "aa";
            this.DropDownList1.DataValueField = "bb";
            this.DropDownList1.DataBind();
            foreach (ListItem item in  this.DropDownList1.Items)
            {
                if (item.Value.ToString() == "1")
                {
                    item.Selected = true;
                    break;
                }
            }

楼上的我明白你的思路了，谢谢我想请问一下我是用控制SqlDataSource2的，我如何获取数据的集合表万分感谢

直接连接就是了配置一下你的数据连接字符串和sql语句

如果2个表有直接或间接关系，应该为两个表建立外键关系，这样的话实现DropDownList 联动就简单得多。

先将数据绑上
再用SelectedValue属性来设置

将数据绑上去后再用DropDownList1.SelectedValue=“1”这个属性来设置下，搞定

楼上的我也知道DropDownList1.SelectedValue=“1”就可以默认值了，可我要求的是自动判断的

我非常喜欢这种写法。实际开发使用时，应该注意 BindRateName() 内部应该首先查询数据缓存，用查询Sql语句作为缓存单元的key进行查询，当没有缓存时才真正查询数据库。

楼主并没有说明怎么知道“默认值”是什么，所以很难回答。假设默认值使用页面上一个 GetDefaultValue() 方法来返回，那么那一行就可以设置为：DataSource = '<%# BindRateName() %>' SelectedValue='<%# GetDefaultValue() %>'

我已经说明了当bb=1时DropDownList默认就是F3

绑定DropDownList后用Foreach遍历下...

ddropdownlist 有 text 和 value 两个属性的当text == 11 value 等于 F3

this.DropDownList1.DataValueField = "bb";
this.DropDownList1.DataTextField = "aa";

  datatable dt=取出数据.
  this.DropDownList1.DataSource = dt;
  this.DropDownList1.DataValueField = "bb";
  this.DropDownList1.DataTextField = "aa";
  this.DropDownList1.DataBind();

调试易

DropDownList默认值问题，谢了

解决方案 »