我必须在下拉选择的索引更改上更改 GridView 数据

Question

我必须在 DropDown Selected Value Change 上更改 Gridview 详细信息。这是我的代码，但它不起作用。它没有在 GridView 中显示数据。当我更改 DropDownList 的索引时，GridView 为空。

index.aspx.cs 代码：

    protected void DropDownListDoctor_SelectedIndexChanged(object sender, EventArgs e)
    {
        string query = "SELECT * FROM Doctor WHERE Doc_Id=" + DropDownListDoctor.SelectedValue + "";
        DataTable dt = new DataTable();
        SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
        conn.Open();
        SqlDataAdapter da = new SqlDataAdapter(query, conn);
        da.Fill(dt);
        GridViewDoctorDetail.DataSource = dt;
    }

index.aspx 代码：

<form id="form1" runat="server">
<div>
<label>Select Doctor Name</label>
<br />
   <asp:DropDownList ID="DropDownListDoctor" runat="server" AutoPostBack="True" 
        DataSourceID="Doctor_DataSource" DataTextField="DocName" 
        DataValueField="Doc_Id" 
        onselectedindexchanged="DropDownListDoctor_SelectedIndexChanged">
    </asp:DropDownList>
    <asp:SqlDataSource ID="Doctor_DataSource" runat="server" 
        ConnectionString="Data Source=IM-82B70624D72D;Initial Catalog=AppointmentScheduler;Persist Security Info=True;User ID=sa;Password=za3452432760za" 
        ProviderName="System.Data.SqlClient" 
        SelectCommand="SELECT [Doc_Id], [DocName] FROM [Doctor]">
    </asp:SqlDataSource>
    <br />
    <label>Doctor Detail</label>
    <br />
    <asp:GridView ID="GridViewDoctorDetail" runat="server" BackColor="White" 
        BorderColor="#DEDFDE" BorderStyle="None" BorderWidth="1px" CellPadding="4" 
        ForeColor="Black" GridLines="Vertical" Width="339px" 
        AutoGenerateColumns="False">
        <AlternatingRowStyle BackColor="White" />
        <FooterStyle BackColor="#CCCC99" />
        <HeaderStyle BackColor="#6B696B" Font-Bold="True" ForeColor="White" />
        <PagerStyle BackColor="#F7F7DE" ForeColor="Black" HorizontalAlign="Right" />
        <RowStyle BackColor="#F7F7DE" />
        <SelectedRowStyle BackColor="#CE5D5A" Font-Bold="True" ForeColor="White" />
        <SortedAscendingCellStyle BackColor="#FBFBF2" />
        <SortedAscendingHeaderStyle BackColor="#848384" />
        <SortedDescendingCellStyle BackColor="#EAEAD3" />
        <SortedDescendingHeaderStyle BackColor="#575357" />
    </asp:GridView>
    <asp:SqlDataSource ID="DoctorDetail_SqlDataSource" runat="server" 
        ConnectionString="Data Source=IM-82B70624D72D;Initial Catalog=AppointmentScheduler;Persist Security Info=True;User ID=sa;Password=za3452432760za" 
        ProviderName="System.Data.SqlClient" 
        SelectCommand="SELECT * FROM [Doctor] WHERE ([Doc_Id] = @Doc_Id)">
        <SelectParameters>
            <asp:ControlParameter ControlID="DropDownListDoctor" DefaultValue="1" 
                Name="Doc_Id" PropertyName="SelectedValue" Type="Int32" />
        </SelectParameters>
    </asp:SqlDataSource>
</div>
</form>

Answer 1

你需要添加

GridViewDoctorDetail.DataBind();

到您的后台代码。当回发发生时，gridview 会丢失其先前的内容，并且没有任何数据绑定到它。

protected void DropDownListDoctor_SelectedIndexChanged(object sender, EventArgs e)
{
    string query = "SELECT * FROM Doctor WHERE Doc_Id=" + DropDownListDoctor.SelectedValue + "";
    DataTable dt = new DataTable();
    SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
    conn.Open();
    SqlDataAdapter da = new SqlDataAdapter(query, conn);
    da.Fill(dt);
    GridViewDoctorDetail.DataSource = dt;
    GridViewDoctorDetail.DataBind();
}