Question

dropdownlist 联动 ，第二个dropdownlist的取值总是（第一个选项）怎么解决？

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
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;
using System.Xml.Linq;
using webwinscom.DAL.proClassIdTableAdapters;

namespace webwinscom.admin
{
public partial class addpro : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{

}
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
string x = DropDownList1.SelectedValue;
string xx = "SELECT [Pro_name], [pro_ClassId] FROM [Pro_NameID] where pro_ClassId=" + x;

SqlDataSource2.SelectCommand = xx;
}

}
}

Answer 1

dropdownlist 联动
第一个dropdownlist的属性AutoPostBack设置成True （当选定的内容更改后，自动会发到服务器。）
-----------代码如下----参考用-----------------------------
SqlConnection conn;
SqlCommand cmd;
protected void Page_Load(object sender, EventArgs e)
{
ddl1.Items.Add(new ListItem("请选择", ""));
ddl2.Items.Add(new ListItem("请选择", ""));
conn = new SqlConnection("-------连接数据库-----");
if (conn.State == ConnectionState.Closed)
{
conn.Open();
}

string strsql = "select *from sity where sdd=0";
cmd = new SqlCommand(strsql, conn);
SqlDataReader dr = cmd.ExecuteReader();

if (!this.IsPostBack)
{
if (!dr.HasRows)
{
return;
}

while (dr.Read())
{
ddl1.Items.Add(new ListItem(dr["sname"].ToString(), dr["sid"].ToString()));
}
conn.Close();
dr.Close();
}
}

protected void ddl1_SelectedIndexChanged(object sender, EventArgs e)
{
ddl2.Items.Clear();
if (conn.State == ConnectionState.Closed)
{
conn.Open();
}

string strsql = "select * from sity where sdd=" + Convert.ToInt32(ddl1.SelectedValue);
cmd = new SqlCommand(strsql, conn);
SqlDataReader dr = cmd.ExecuteReader();
if (!dr.HasRows)
{
return;
}
while (dr.Read())
{
ddl2.Items.Add(new ListItem(dr["sname"].ToString(), dr["sid"].ToString()));
}
conn.Close();
dr.Close();
}

Answer 2

以上回答均胡扯，拜托你们好好看看别人的代码再回答呀
但从你的代码看，只能看出不存在他们所说的问题，具体什么问题请贴详细点

Answer 3

你断点看一下,估计是postback的时候改回去了

Answer 4

dropdownlist的AutoPostBack属性设为true了吗？

Answer 5

能不能把代码补全点?..