ASP.net DropDownList 填充 GridView

Question

我正在尝试设置 GridView 来过滤属于特定员工的凭据。下拉列表提供员工列表，一旦选中，我希望 gridview 仅填充属于特定员工的条目。

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
    <asp:DropDownList ID="DropDownListEmployee" runat="server"  
                      AutoPostBack="True" 
                      OnSelectedIndexChanged="SelectionHasChanged"
                      DataSourceID="SqlDataSource2" DataTextField="Fullname"
                      DataValueField="Employee_ID" AppendDataBoundItems="true"
                      Width="214px">
        <asp:ListItem>Select</asp:ListItem>
    </asp:DropDownList>
    <asp:SqlDataSource ID="SqlDataSource2" runat="server" 
                       ConnectionString="<%$ ConnectionStrings:DBConnectionString %>" 
                       SelectCommand="SELECT Employee.F_Name + ' ' + Employee.L_Name AS Fullname, Employee.Primary_Address, Employee.Primary_Phone, Employee.E_mail, Credentials.Degree, Credentials.Years_Experience, Credentials.Certifications, Credentials.Positions, Employee.Employee_ID FROM Employee INNER JOIN Credentials ON Employee.Employee_ID = Credentials.Employee_ID"></asp:SqlDataSource>
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
                  DataSourceID="SqlDataSource2" DataKeyNames="Employee_ID">
        <Columns> 
            <asp:BoundField DataField="Fullname" HeaderText="Fullname" 
                            ReadOnly="True" SortExpression="Fullname" />
            <asp:BoundField DataField="Primary_Address" HeaderText="Primary_Address" 
                            SortExpression="Primary_Address" />
            <asp:BoundField DataField="Primary_Phone" HeaderText="Primary_Phone" 
                            SortExpression="Primary_Phone" />
            <asp:BoundField DataField="E_mail" HeaderText="E_mail" 
                            SortExpression="E_mail" />
            <asp:BoundField DataField="Degree" HeaderText="Degree" 
                            SortExpression="Degree" />
            <asp:BoundField DataField="Years_Experience" HeaderText="Years_Experience" 
                            SortExpression="Years_Experience" />
            <asp:BoundField DataField="Certifications" HeaderText="Certifications" 
                            SortExpression="Certifications" />
            <asp:BoundField DataField="Positions" HeaderText="Positions" 
                            SortExpression="Positions" />
            <asp:BoundField DataField="Employee_ID" HeaderText="Employee_ID" 
                            InsertVisible="False" ReadOnly="True" 
                            SortExpression="Employee_ID" />
        </Columns>
    </asp:GridView>
</asp:Content>

Answer 1

你没有说你当前的代码会发生什么，但我敢打赌，当你选择一个员工时，页面会重新加载，你会得到一个数据库中所有员工的列表，对吧？

如果这是真的，原因是同一个 SqlDataSource 绑定到您的 DropDownList 和 GridView，并且 SqlDataSource 的 Select 命令检索所有员工 - 没有 WHERE 条件来选择所需的员工。

我将使用 2 个 SqlDataSource - 一个用于 DropDownList，一个用于 GridView。第二个 SqlDataSource 将有一个 Select 命令来根据 DropDownList 中的选择获取所需员工的信息。

您可以修改 SqlDataSource2 的 SelectCommand 以仅返回 fullname 和 EmployeeID 字段，因为 DropDownList 不需要其余字段：

<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
    <asp:DropDownList ID="DropDownListEmployee" runat="server"  
                      AutoPostBack="True" 
                      OnSelectedIndexChanged="SelectionHasChanged"
                      DataSourceID="SqlDataSource2" DataTextField="Fullname"
                      DataValueField="Employee_ID" AppendDataBoundItems="true"
                      Width="214px">
        <asp:ListItem>Select</asp:ListItem>
    </asp:DropDownList>
    <asp:SqlDataSource ID="SqlDataSource2" runat="server" 
                       ConnectionString="<%$ ConnectionStrings:DBConnectionString %>" 
                       SelectCommand="SELECT F_Name + ' ' + L_Name AS Fullname, Employee_ID FROM Employee"></asp:SqlDataSource>

在您的第二个 SqlDataSource 中，您需要向 SelectParameters 集合添加一个参数 (EmployeeID)，如下所示，并更新您的 SelectCommand 以获取该参数。

    <asp:SqlDataSource ID="gvDataSource" runat="server"
                       ConnectionString="<%$ ConnectionStrings:DBConnectionString %>"
                       SelectCommand="SELECT Employee.F_Name + ' ' + Employee.L_Name AS Fullname, Employee.Primary_Address, Employee.Primary_Phone, Employee.E_mail, Credentials.Degree, Credentials.Years_Experience, Credentials.Certifications, Credentials.Positions, Employee.Employee_ID FROM Employee INNER JOIN Credentials ON Employee.Employee_ID = Credentials.Employee_ID WHERE Employee.EmployeeID = IsNull(@EmployeeID, EmployeeID)">
        <SelectParameters>
            <asp:ControlParameter ControlID="DropDownListID" 
                 ConvertEmptyStringToNull="true" Name="EmployeeID"
                 PropertyName="SelectedValue" />
        </SelectParameters>

然后将这个 SqlDataSource 分配给 GridView 而不是第一个。

请注意，SqlDataSource 不会对提交到参数中的值进行验证 - 这可能会造成安全威胁。

SqlDataSource.Select Method

SqlDataSource.SelectParameters Property