c# 两个dropdownlist,第一个正常,第二个为什么点击了选项之后框里面显示的总是第一项
具体说明请看http://zhidao.baidu.com/question/492614125.html?quesup2#在线等啊
哦,是为二级联动 --------------------编程问答-------------------- 去掉第二个dropdownlist的autopostback撒，你回发后第二个下拉框重新绑定了，自然又回到第一个去了 --------------------编程问答-------------------- 去掉了啦,可是结果还是一样的,并且第二个dropdownlist的DropDownListMajor_SelectedIndexChanged事件无法触发.这又是为什么? --------------------编程问答--------------------
<asp:DropDownList ID="DropDownList1" runat="server" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged" AutoPostBack="true">
</asp:DropDownList>
<asp:DropDownList ID="DropDownList2" runat="server" OnSelectedIndexChanged="DropDownList2_SelectedIndexChanged" AutoPostBack="true">
</asp:DropDownList>
--------------------编程问答-------------------- Refer:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
//定义数据表
DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("ID", typeof(int)));
dt.Columns.Add(new DataColumn("Class", typeof(string)));
for (int i = 1; i < 7; i++)
{
DataRow drr = dt.NewRow();
drr["ID"] = i;
drr["Class"] = i.ToString() + "年级";
dt.Rows.Add(drr);
}
//绑定下拉
DropDownList1.DataSource = dt;
DropDownList1.DataTextField = "Class";
DropDownList1.DataValueField = "ID";
DropDownList1.DataBind();
DropDownList1.Items.Insert(0, new ListItem("", "-1"));
}
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
//这里你根据自己的实际情况判断后绑定
if (DropDownList1.SelectedItem.Value == "1")
{
DropDownList2.Items.Add(new ListItem("学生1", "1"));
DropDownList2.Items.Add(new ListItem("学生2", "2"));
DropDownList2.Items.Insert(0, new ListItem("", "-1"));
}
}
protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
{
string MM=DropDownList1.SelectedItem.Text.ToString()+DropDownList2.SelectedItem.Text.ToString();
Response.Write(MM);//输出两个下拉框的选择项
}
http://www.cnblogs.com/insus/archive/2011/07/04/2097059.html
http://www.cnblogs.com/insus/archive/2012/10/16/2725307.html --------------------编程问答-------------------- --------------------编程问答-------------------- 用ajax都好 还省得去刷新 --------------------编程问答--------------------
DDL.Items.FindByValue("").seleced=true 是用 FindByValue这个就好了 --------------------编程问答--------------------
--------------------编程问答-------------------- 关键要加：AutoPostBack="True" --------------------编程问答-------------------- 一般都是数据错了，值相同了 --------------------编程问答-------------------- AutoPostBack="True" 这时候才能触发你的DropDownListMajor_SelectedIndexChanged事件
<asp:DropDownList Width="100" ID="DropDownList1" runat="server" DataSourceID="SqlDataSource1" DataTextField="name" DataValueField="ID" AutoPostBack="True"></asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SELECT * FROM [aa]">
</asp:SqlDataSource>
<asp:DropDownList Width="100" ID="DropDownList2" runat="server" DataSourceID="SqlDataSource2" DataTextField="Sex" DataValueField="ID" AutoPostBack="True"></asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SELECT * FROM [cc] WHERE ([ID] = @ID)">
<SelectParameters>
<asp:ControlParameter ControlID="DropDownList1" DefaultValue="1" Name="ID" PropertyName="SelectedValue" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
而AutoPostBack="True" 的话优惠影响你的绑定
所以你需要把你的绑定放到
if(!IsPostBack)
{
}
这样第一次调用的时候绑定数据，post back的时候用你选中的那个（ViewState记住了你上次的选择，在页面load后会为你赋值） --------------------编程问答--------------------
同意
补充：.NET技术 , ASP.NET
