Dropdownlist
从数据库中读取其值并显示它们。当页面加载dropdownlist
什么都没有显示(即selectedindex
= -1)和用户选择值时,我想要。任何想法?
答案 0 :(得分:3)
添加空的未绑定项
<asp:DropDownList runat="server" AppendDataBoundItems="true">
<asp:ListItem Selected="true" Text="" Value="" />
</asp:DropDownList>
答案 1 :(得分:0)
您可以从后端添加空数据列表项,也可以直接从下拉列表中添加:
从数据库侧:
SELECT
1 as SortOrder,
DataValueField,
DataTextField
FROM
YourTable
UNION ALL
SELECT
0 As SortOrder, --this ensures the empty item is at the top of the list
0 As DataValueField,
'' As DataTextField --or 'Select One'
Order By
SortOrder,
Value
或直接作为列表项
<asp:ListItem Selected="True" Text="Select One" Value="0" AppendDataBoundItems="true" />