Question

在我的应用程序中，我有2个删除列表，我填充了来自2个相关表的信息和一个标签，用于存储与两者相关的ID。

<asp:DropDownList ID="ddlMedType" runat="server" DataSourceID="sdsMedType"
DataTextField="MedType" DataValueField="MedType" AppendDataBoundItems="True" 
AutoPostBack="True" OnSelectedIndexChanged="ddlMedType_SelectedIndexChanged">
    <asp:ListItem Selected="True">Select Medication Type</asp:ListItem>
</asp:DropDownList>

<asp:SqlDataSource ID="sdsMedType" runat="server" 
ConnectionString="<%$ ConnectionStrings:SqlDataSource2 %>" 
SelectCommand="SELECT [num], [MedType] FROM [pharm_medication_Type]">   
</asp:SqlDataSource>
<asp:Label ID="lblMedType" runat="server" Visible="true"/>

<asp:DropDownList ID="ddlMedication" runat="server" DataSourceID="sdsMedication"
DataTextField="MedName" DataValueField="MedName">
</asp:DropDownList>

<asp:SqlDataSource ID="sdsMedication" runat="server" 
ConnectionString="<%$ ConnectionStrings:SqlDataSource2 %>" 
SelectCommand="SELECT [MedName] FROM [pharm_medications] WHERE ([num] = @num)">

<SelectParameters>    
<asp:ControlParameter ControlID="lblMedType" Name="num" PropertyName="Text" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>

这里在我后面的代码中填充标签以获取相关表的id

protected void ddlMedType_SelectedIndexChanged(object sender, EventArgs e)
    {
        string strMedType = ddlMedType.SelectedValue;
        SqlCommand cmd1 = new SqlCommand("SELECT [num] from [pharm_medication_Type] where [MedType] = '" + strMedType + "'", conn1);
        cmd1.CommandType = CommandType.Text;
        conn1.Open();
        int Result1 = Convert.ToInt32(cmd1.ExecuteScalar());
        lblMedType.Text = Result1.ToString();
        conn1.Dispose();
        cmd1.Dispose();
    }

但是当我运行应用程序时，除第二个选项外，所有选项都有效。为什么呢？

Answer 1

我建议您直接将ddlMedType用于<asp:ControlParameter>，并且不要使用分隔标签来获取ID，只需设置DataTextField和DataValueField ddlMedType正确而且足够。请更改您的代码如下：

<asp:DropDownList ID="ddlMedType" runat="server" DataSourceID="sdsMedType"
DataTextField="MedType" DataValueField="num" AppendDataBoundItems="True" 
AutoPostBack="True" OnSelectedIndexChanged="ddlMedType_SelectedIndexChanged">
    <asp:ListItem Selected="True" value="0">Select Medication Type</asp:ListItem>
</asp:DropDownList>

<asp:SqlDataSource ID="sdsMedType" runat="server" 
ConnectionString="<%$ ConnectionStrings:SqlDataSource2 %>" 
SelectCommand="SELECT [num], [MedType] FROM [pharm_medication_Type]">   
</asp:SqlDataSource>

<asp:DropDownList ID="ddlMedication" runat="server" DataSourceID="sdsMedication"
DataTextField="MedName" DataValueField="MedName">
</asp:DropDownList>

<asp:SqlDataSource ID="sdsMedication" runat="server" 
ConnectionString="<%$ ConnectionStrings:SqlDataSource2 %>" 
SelectCommand="SELECT [MedName] FROM [pharm_medications] WHERE ([num] = @num)">

<SelectParameters>    
<asp:ControlParameter ControlID="ddlMedType" Name="num" PropertyName="SelectedValue" />
</SelectParameters>
</asp:SqlDataSource>

并删除事件背后代码的代码如下：

protected void ddlMedType_SelectedIndexChanged(object sender, EventArgs e)
    {}

希望这对你有所帮助。

数据绑定DropList第二个选项将不会填充

1 个答案: