我有两个下拉列表(一个动态填充,另一个没有)确定第三个下拉列表的值。这个想法是,第一个ddl1是强制性的,ddl2是可选的。一旦选择了ddl1值,如何获得ddl2的空值(不是值被选中)。谢谢!背后通过两个独立(不级联)的下拉列表动态填充第三个下拉列表
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:conn %>" SelectCommand="SELECT Category FROM Categories"></asp:SqlDataSource>
<asp:DropDownList ID="DropDownList1" AutoPostBack="True" runat="server" DataSourceID="SqlDataSource1" DataTextField="Category" DataValueField="Category" AppendDataBoundItems="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
<asp:ListItem Text="Select category" Value=""/>
</asp:DropDownList>
<asp:DropDownList ID="DropDownList2" runat="server">
<asp:ListItem Text="All types" Value="" />
<asp:ListItem Value="Policy">Policy</asp:ListItem>
<asp:ListItem Value="Form">Form</asp:ListItem>
<asp:ListItem Value="Other">Other</asp:ListItem>
</asp:DropDownList>
<asp:DropDownList ID="DropDownList3" runat="server" DataSourceID="SqlDataSource3" DataTextField="DocName" DataValueField="DocID" AppendDataBoundItems="True">
<asp:ListItem Text="Select document" Value=""/>
</asp:DropDownList>
代码:
Protected Sub DropDownList1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
DropDownList3.Items.Clear()
DropDownList3.Items.Add(New ListItem("Select document", ""))
If (DropDownList1.SelectedIndex <> 0 Or DropDownList1.SelectedIndex > 0) Then
SqlDataSource3.SelectCommand = "SELECT DocID, DocName, Category, DocType FROM Doc_LibraryTable WHERE (Category = @Cat) AND (DocType = @DocType OR @DocType IS NULL)"
Dim controlDdl1 As ControlParameter = New ControlParameter
controlDdl1.ControlID = "DropDownList1"
controlDdl1.Name = "Cat"
controlDdl1.Type = TypeCode.String
controlDdl1.PropertyName = "SelectedValue"
SqlDataSource3.SelectParameters.Clear()
SqlDataSource3.SelectParameters.Add(controlDdl1)
Dim controlDdl2 As ControlParameter = New ControlParameter
controlDdl2.ControlID = "DropDownList2"
controlDdl2.Name = "DocType"
controlDdl2.Type = TypeCode.String
controlDdl2.PropertyName = "SelectedValue"
SqlDataSource3.SelectParameters.Clear()
SqlDataSource3.SelectParameters.Add(controlDdl2)
SqlDataSource3.SelectParameters("DocType").DefaultValue = ""
End If
End Sub
非常感谢您的帮助。我得到它的工作! – netNewbi3 2010-07-13 12:35:20