如何根据来自其他 DropDownList 的选择进行多个 DropDownList 更改答案

【问题标题】：How to make multiple DropDownList change based on selection from other DropDownList如何根据来自其他 DropDownList 的选择进行多个 DropDownList 更改
【发布时间】：2014-08-14 13:17:56
【问题描述】：

我有以下 ASP.net 代码用于过滤我的GridView：

<asp:UpdatePanel runat="server" ClientIDMode="Static" ID="TasksUpdatePanel" UpdateMode="Conditional">
    <ContentTemplate>
        <table style="width: 100%; padding: 0; margin: 0; border: 0; border-spacing: 0; border-collapse: separate;" class="GridviewTable">
            <tr>
                <td style="width: 25%;">
                    <asp:DropDownList ID="ddlTaskName" CssClass="chosen-select" DataSourceID="dsPopulateTaskName" AutoPostBack="true" DataValueField="Task Name" runat="server" Width="100%" Font-Size="11px" AppendDataBoundItems="true" OnSelectedIndexChanged="ddlTaskName_onSelectIndexChanged">
                        <asp:ListItem Text="All" Value="%"></asp:ListItem>
                    </asp:DropDownList>
                    <asp:SqlDataSource ID="dsPopulateTaskName" runat="server" ConnectionString="<%$ ConnectionStrings:gvConnString %>" SelectCommand="SELECT DISTINCT [ATTR2739] 'Task Name' FROM HSI.RMOBJECTINSTANCE1224 CT INNER JOIN HSI.RMOBJECTINSTANCE1232 S ON CT.ATTR2846 = S.ATTR2821 INNER JOIN HSI.USERACCOUNT UA ON S.FK2852 = (UA.USERNUM * -1) WHERE CT.ACTIVESTATUS = 0"></asp:SqlDataSource>
                </td>
                <td style="width: 20%;">
                    <asp:DropDownList ID="ddlService" CssClass="chosen-select" DataSourceID="dsPopulateService" AutoPostBack="true" DataValueField="Service" runat="server" Width="100%" Font-Size="11px" AppendDataBoundItems="true" OnSelectedIndexChanged="ddlService_onSelectIndexChanged">
                        <asp:ListItem Text="All" Value="%"></asp:ListItem>
                    </asp:DropDownList>
                    <asp:SqlDataSource ID="dsPopulateService" runat="server" ConnectionString="<%$ ConnectionStrings:gvConnString %>" SelectCommand="SELECT DISTINCT [ATTR2846] 'Service' FROM HSI.RMOBJECTINSTANCE1224 CT INNER JOIN HSI.RMOBJECTINSTANCE1232 S ON CT.ATTR2846 = S.ATTR2821 INNER JOIN HSI.USERACCOUNT UA ON S.FK2852 = (UA.USERNUM * -1) WHERE CT.ACTIVESTATUS = 0"></asp:SqlDataSource>
                </td>
                <td style="width: 11%;">
                    <asp:DropDownList ID="ddlStatus" CssClass="chosen-select" DataSourceID="dsPopulateStatus" AutoPostBack="true" DataValueField="Status" runat="server" Width="100%" Font-Size="11px" AppendDataBoundItems="true" OnSelectedIndexChanged="ddlStatus_onSelectIndexChanged">
                        <asp:ListItem Text="All" Value="%"></asp:ListItem>
                    </asp:DropDownList>
                    <asp:SqlDataSource ID="dsPopulateStatus" runat="server" ConnectionString="<%$ ConnectionStrings:gvConnString %>" SelectCommand="SELECT DISTINCT [ATTR2812] 'Status' FROM HSI.RMOBJECTINSTANCE1224 CT INNER JOIN HSI.RMOBJECTINSTANCE1232 S ON CT.ATTR2846 = S.ATTR2821 INNER JOIN HSI.USERACCOUNT UA ON S.FK2852 = (UA.USERNUM * -1) WHERE CT.ACTIVESTATUS = 0"></asp:SqlDataSource>
                </td>
                <td style="width: 14%;">
                    <asp:DropDownList ID="ddlDueDate" CssClass="chosen-select" DataSourceID="dsPopulateDueDate" AutoPostBack="true" DataValueField="Due Date" runat="server" Width="100%" Font-Size="11px" AppendDataBoundItems="true" OnSelectedIndexChanged="ddlDueDate_onSelectIndexChanged">
                        <asp:ListItem Text="All" Value="%"></asp:ListItem>
                    </asp:DropDownList>
                    <asp:SqlDataSource ID="dsPopulateDueDate" runat="server" ConnectionString="<%$ ConnectionStrings:gvConnString %>" SelectCommand="SELECT DISTINCT CONVERT(VARCHAR(14), [ATTR2752], 110) 'Due Date' FROM HSI.RMOBJECTINSTANCE1224 CT INNER JOIN HSI.RMOBJECTINSTANCE1232 S ON CT.ATTR2846 = S.ATTR2821 INNER JOIN HSI.USERACCOUNT UA ON S.FK2852 = (UA.USERNUM * -1) WHERE CT.ACTIVESTATUS = 0"></asp:SqlDataSource>
                </td>
                <td style="width: 15%;">
                    <asp:DropDownList ID="ddlOwner" CssClass="chosen-select" DataSourceID="dsPopulateOwner" AutoPostBack="true" DataValueField="Owner" runat="server" Width="100%" Font-Size="11px" AppendDataBoundItems="true" OnSelectedIndexChanged="ddlOwner_onSelectIndexChanged">
                        <asp:ListItem Text="All" Value="%"></asp:ListItem>
                    </asp:DropDownList>
                    <asp:SqlDataSource ID="dsPopulateOwner" runat="server" ConnectionString="<%$ ConnectionStrings:gvConnString %>" SelectCommand="SELECT DISTINCT [REALNAME] 'Owner' FROM HSI.RMOBJECTINSTANCE1224 CT INNER JOIN HSI.RMOBJECTINSTANCE1232 S ON CT.ATTR2846 = S.ATTR2821 INNER JOIN HSI.USERACCOUNT UA ON S.FK2852 = (UA.USERNUM * -1) WHERE CT.ACTIVESTATUS = 0"></asp:SqlDataSource>
                </td>
                <td style="width: 15%;">
                    <asp:DropDownList ID="ddlClient" CssClass="chosen-select" DataSourceID="dsPopulateClient" AutoPostBack="true" DataValueField="Client" runat="server" Width="100%" Font-Size="11px" AppendDataBoundItems="true" OnSelectedIndexChanged="ddlClient_onSelectIndexChanged">
                        <asp:ListItem Text="All" Value="%"></asp:ListItem>
                    </asp:DropDownList>
                    <asp:SqlDataSource ID="dsPopulateClient" runat="server" ConnectionString="<%$ ConnectionStrings:gvConnString %>" SelectCommand="SELECT DISTINCT [ATTR2799] 'Client' FROM HSI.RMOBJECTINSTANCE1224 CT INNER JOIN HSI.RMOBJECTINSTANCE1232 S ON CT.ATTR2846 = S.ATTR2821 INNER JOIN HSI.USERACCOUNT UA ON S.FK2852 = (UA.USERNUM * -1) WHERE CT.ACTIVESTATUS = 0"></asp:SqlDataSource>
                </td>
            </tr>
        </table>
        <asp:GridView ShowHeaderWhenEmpty="false" AlternatingRowStyle-BackColor="#EBE9E9" AutoGenerateColumns="false" OnSorting="yourTasksGV_Sorting" AllowSorting="true" ID="yourTasksGV" runat="server" ClientIDMode="Static" EmptyDataText="There is no data to display" OnRowDataBound="yourTasksGV_RowDataBound" OnRowCreated="yourTasksGV_RowCreated">
            <Columns>
                <asp:HyperLinkField Target="_blank" DataNavigateUrlFields="Task Detail" DataTextField="Task Name" DataNavigateUrlFormatString="" HeaderText="Task Detail" SortExpression="Task Name" ItemStyle-Width="25%" ItemStyle-CssClass="taskTableColumn" />
                <asp:BoundField DataField="Service" HeaderText="Service" SortExpression="Service" ItemStyle-Width="20%" ItemStyle-CssClass="taskTableColumn" />
                <asp:BoundField DataField="Status" HeaderText="Status" SortExpression="Status" ItemStyle-Width="10%" ItemStyle-CssClass="taskTableColumn" />
                <asp:BoundField DataField="Due Date" HeaderText="Due Date" SortExpression="Due Date" ItemStyle-Width="15%" ItemStyle-CssClass="taskTableColumn" />
                <asp:BoundField DataField="Owner" HeaderText="Owner" SortExpression="Owner" ItemStyle-Width="15%" ItemStyle-CssClass="taskTableColumn" />
                <asp:BoundField DataField="Client" HeaderText="Client" SortExpression="Client" ItemStyle-Width="15%" ItemStyle-CssClass="taskTableColumn" />
            </Columns>
        </asp:GridView>
    </ContentTemplate>
</asp:UpdatePanel>

我上面的 ASP.net 页面的代码隐藏：

protected void ddlTaskName_onSelectIndexChanged(object sender, EventArgs e)
{
    string query = "";
    string strText = ddlTaskName.SelectedItem.Text;
    ddlService.SelectedIndex = 0;
    ddlStatus.SelectedIndex = 0;
    ddlDueDate.SelectedIndex = 0;
    ddlClient.SelectedIndex = 0;
    ddlOwner.SelectedIndex = 0;
    //MessageBox.Show(strText);

    DataTable taskData = new DataTable();
    if (strText == "All")
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0";
    }
    else
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND CT.ATTR2739 = '" + strText + "'";
    }

    using (SqlConnection conn = new SqlConnection(connString))
    {
        try
        {
            SqlCommand cmd = new SqlCommand(query, conn);

            // create data adapter
            SqlDataAdapter da = new SqlDataAdapter(query, conn);
            // this will query your database and return the result to your datatable

            DataSet myDataSet = new DataSet();
            da.Fill(myDataSet);

            DataView myDataView = new DataView();
            myDataView = myDataSet.Tables[0].DefaultView;

            if (ViewState["sortExp"].ToString() != string.Empty)
            {
                //MessageBox.Show(sortExp);
                //MessageBox.Show(sortDir);
                myDataView.Sort = string.Format("{0} {1}", ViewState["sortExp"].ToString(), ViewState["sortOrder"].ToString());
            }

            yourTasksGV.DataSource = myDataView;
            yourTasksGV.DataBind();

            TasksUpdatePanel.Update();

            conn.Close();
        }
        catch (Exception ex)
        {
            string error = ex.Message;
        }
    }
}
protected void ddlOwner_onSelectIndexChanged(object sender, EventArgs e)
{
    string query = "";
    string strText = ddlOwner.SelectedItem.Text;
    ddlService.SelectedIndex = 0;
    ddlStatus.SelectedIndex = 0;
    ddlDueDate.SelectedIndex = 0;
    ddlClient.SelectedIndex = 0;
    ddlTaskName.SelectedIndex = 0;
    //MessageBox.Show(strText);

    DataTable taskData = new DataTable();
    if (strText == "All")
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0";
    }
    else
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND UA.REALNAME = '" + strText + "'";
    }

    using (SqlConnection conn = new SqlConnection(connString))
    {
        try
        {
            SqlCommand cmd = new SqlCommand(query, conn);

            // create data adapter
            SqlDataAdapter da = new SqlDataAdapter(query, conn);
            // this will query your database and return the result to your datatable

            DataSet myDataSet = new DataSet();
            da.Fill(myDataSet);

            DataView myDataView = new DataView();
            myDataView = myDataSet.Tables[0].DefaultView;

            if (ViewState["sortExp"].ToString() != string.Empty)
            {
                //MessageBox.Show(sortExp);
                //MessageBox.Show(sortDir);
                myDataView.Sort = string.Format("{0} {1}", ViewState["sortExp"].ToString(), ViewState["sortOrder"].ToString());
            }

            yourTasksGV.DataSource = myDataView;
            yourTasksGV.DataBind();

            TasksUpdatePanel.Update();

            conn.Close();
        }
        catch (Exception ex)
        {
            string error = ex.Message;
        }
    }
}
protected void ddlService_onSelectIndexChanged(object sender, EventArgs e)
{
    string query = "";
    string strText = ddlService.SelectedItem.Text;
    ddlTaskName.SelectedIndex = 0;
    ddlStatus.SelectedIndex = 0;
    ddlDueDate.SelectedIndex = 0;
    ddlClient.SelectedIndex = 0;
    ddlOwner.SelectedIndex = 0;
    //MessageBox.Show(strText);

    DataTable taskData = new DataTable();
    if (strText == "All")
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0";
    }
    else
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND CT.ATTR2846 = '" + strText + "'";
    }

    using (SqlConnection conn = new SqlConnection(connString))
    {
        try
        {
            SqlCommand cmd = new SqlCommand(query, conn);

            // create data adapter
            SqlDataAdapter da = new SqlDataAdapter(query, conn);
            // this will query your database and return the result to your datatable

            DataSet myDataSet = new DataSet();
            da.Fill(myDataSet);

            DataView myDataView = new DataView();
            myDataView = myDataSet.Tables[0].DefaultView;

            if (ViewState["sortExp"].ToString() != string.Empty)
            {
                //MessageBox.Show(sortExp);
                //MessageBox.Show(sortDir);
                myDataView.Sort = string.Format("{0} {1}", ViewState["sortExp"].ToString(), ViewState["sortOrder"].ToString());
            }

            yourTasksGV.DataSource = myDataView;
            yourTasksGV.DataBind();

            TasksUpdatePanel.Update();

            conn.Close();
        }
        catch (Exception ex)
        {
            string error = ex.Message;
        }
    }
}
protected void ddlStatus_onSelectIndexChanged(object sender, EventArgs e)
{
    string query = "";
    string strText = ddlStatus.SelectedItem.Text;
    ddlService.SelectedIndex = 0;
    ddlTaskName.SelectedIndex = 0;
    ddlDueDate.SelectedIndex = 0;
    ddlClient.SelectedIndex = 0;
    ddlOwner.SelectedIndex = 0;
    //MessageBox.Show(strText);

    DataTable taskData = new DataTable();
    if (strText == "All")
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0";
    }
    else
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND CT.ATTR2812 = '" + strText + "'";
    }

    using (SqlConnection conn = new SqlConnection(connString))
    {
        try
        {
            SqlCommand cmd = new SqlCommand(query, conn);

            // create data adapter
            SqlDataAdapter da = new SqlDataAdapter(query, conn);
            // this will query your database and return the result to your datatable

            DataSet myDataSet = new DataSet();
            da.Fill(myDataSet);

            DataView myDataView = new DataView();
            myDataView = myDataSet.Tables[0].DefaultView;

            if (ViewState["sortExp"].ToString() != string.Empty)
            {
                //MessageBox.Show(sortExp);
                //MessageBox.Show(sortDir);
                myDataView.Sort = string.Format("{0} {1}", ViewState["sortExp"].ToString(), ViewState["sortOrder"].ToString());
            }

            yourTasksGV.DataSource = myDataView;
            yourTasksGV.DataBind();

            TasksUpdatePanel.Update();

            conn.Close();
        }
        catch (Exception ex)
        {
            string error = ex.Message;
        }
    }
}
protected void ddlDueDate_onSelectIndexChanged(object sender, EventArgs e)
{
    string query = "";
    string strText = ddlDueDate.SelectedItem.Text;
    ddlService.SelectedIndex = 0;
    ddlStatus.SelectedIndex = 0;
    ddlTaskName.SelectedIndex = 0;
    ddlClient.SelectedIndex = 0;
    ddlOwner.SelectedIndex = 0;
    //MessageBox.Show(strText);

    DataTable taskData = new DataTable();
    if (strText == "All")
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0";
    }
    else
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND CONVERT(VARCHAR(14), CT.ATTR2752, 110) = '" + strText + "'";
    }

    using (SqlConnection conn = new SqlConnection(connString))
    {
        try
        {
            SqlCommand cmd = new SqlCommand(query, conn);

            // create data adapter
            SqlDataAdapter da = new SqlDataAdapter(query, conn);
            // this will query your database and return the result to your datatable

            DataSet myDataSet = new DataSet();
            da.Fill(myDataSet);

            DataView myDataView = new DataView();
            myDataView = myDataSet.Tables[0].DefaultView;

            if (ViewState["sortExp"].ToString() != string.Empty)
            {
                //MessageBox.Show(sortExp);
                //MessageBox.Show(sortDir);
                myDataView.Sort = string.Format("{0} {1}", ViewState["sortExp"].ToString(), ViewState["sortOrder"].ToString());
            }

            yourTasksGV.DataSource = myDataView;
            yourTasksGV.DataBind();

            TasksUpdatePanel.Update();

            conn.Close();
        }
        catch (Exception ex)
        {
            string error = ex.Message;
        }
    }
}
protected void ddlClient_onSelectIndexChanged(object sender, EventArgs e)
{
    string query = "";
    string strText = ddlClient.SelectedItem.Text;
    ddlService.SelectedIndex = 0;
    ddlStatus.SelectedIndex = 0;
    ddlDueDate.SelectedIndex = 0;
    ddlTaskName.SelectedIndex = 0;
    ddlOwner.SelectedIndex = 0;
    //MessageBox.Show(strText);

    DataTable taskData = new DataTable();
    if (strText == "All")
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0";
    }
    else
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND CT.ATTR2799 = '" + strText + "'";
    }

    using (SqlConnection conn = new SqlConnection(connString))
    {
        try
        {
            SqlCommand cmd = new SqlCommand(query, conn);

            // create data adapter
            SqlDataAdapter da = new SqlDataAdapter(query, conn);
            // this will query your database and return the result to your datatable

            DataSet myDataSet = new DataSet();
            da.Fill(myDataSet);

            DataView myDataView = new DataView();
            myDataView = myDataSet.Tables[0].DefaultView;

            if (ViewState["sortExp"].ToString() != string.Empty)
            {
                //MessageBox.Show(sortExp);
                //MessageBox.Show(sortDir);
                myDataView.Sort = string.Format("{0} {1}", ViewState["sortExp"].ToString(), ViewState["sortOrder"].ToString());
            }

            yourTasksGV.DataSource = myDataView;
            yourTasksGV.DataBind();

            TasksUpdatePanel.Update();

            conn.Close();
        }
        catch (Exception ex)
        {
            string error = ex.Message;
        }
    }
}

对GridView进行过滤的函数：

public void PullData(string sortExp, string sortDir)
{
    string query = "";
    DataTable taskData = new DataTable();
    connString = ""; //the connection string is here
    if (ddlTaskName.SelectedIndex == 0 && ddlService.SelectedIndex == 0 && ddlStatus.SelectedIndex == 0 && ddlDueDate.SelectedIndex == 0 && ddlOwner.SelectedIndex == 0 && ddlClient.SelectedIndex == 0)
    {
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0";
    }
    else if (ddlTaskName.SelectedIndex > 0)
    {
        string strText = ddlTaskName.SelectedItem.Text;
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND CT.ATTR2739 = '" + strText + "'";
    }
    else if (ddlService.SelectedIndex > 0)
    {
        string strText = ddlService.SelectedItem.Text;
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND CT.ATTR2846 = '" + strText + "'";
    }
    else if (ddlStatus.SelectedIndex > 0)
    {
        string strText = ddlStatus.SelectedItem.Text;
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND CT.ATTR2812 = '" + strText + "'";
    }
    else if (ddlDueDate.SelectedIndex > 0)
    {
        string strText = ddlDueDate.SelectedItem.Text;
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND CONVERT(VARCHAR(14), CT.ATTR2752, 110) = '" + strText + "'";
    }
    else if (ddlOwner.SelectedIndex > 0)
    {
        string strText = ddlClient.SelectedItem.Text;
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND UA.REALNAME = '" + strText + "'";
    }
    else if (ddlClient.SelectedIndex > 0)
    {
        string strText = ddlClient.SelectedItem.Text;
        query = strMainQuery + " WHERE CT.ACTIVESTATUS = 0 AND CT.ATTR2799 = '" + strText + "'";
    }

    using (SqlConnection conn = new SqlConnection(connString))
    {
        try
        {
            SqlCommand cmd = new SqlCommand(query, conn);

            // create data adapter
            SqlDataAdapter da = new SqlDataAdapter(query, conn);
            // this will query your database and return the result to your datatable

            DataSet myDataSet = new DataSet();
            da.Fill(myDataSet);

            DataView myDataView = new DataView();
            myDataView = myDataSet.Tables[0].DefaultView;

            if (sortExp != string.Empty)
            {
                //MessageBox.Show(sortExp);
                //MessageBox.Show(sortDir);
                myDataView.Sort = string.Format("{0} {1}", sortExp, sortDir);
            }

            yourTasksGV.DataSource = myDataView;
            yourTasksGV.DataBind();

            conn.Close();
        }
        catch (Exception ex)
        {
            string error = ex.Message;
        }
    }
}

我想做的是，当用户从DropDownList 之一中选择一个选项时，另一个DropDownList 将更改为过滤后的GridView 的值，但因为DataSource 是硬编码的在，我做不到。

一旦选择了DropDownList，如何从过滤后的GridView 中过滤每个DropDownList？

【问题讨论】：

标签： c# asp.net gridview drop-down-menu

【解决方案1】：

虽然我会彻底建议您使用 parameterized queries，但这应该对您有用（当然，可能需要稍作调整，因为我看不到您的全部代码）

此方法应生成有效的 where 子句。您可以在代码隐藏中的各种OnSelectedIndexChanged 方法中使用此方法，以防止大量复制/粘贴代码。

public string GenerateWhereClause()
{
    List<String> conditions = new List<String>();

    conditions.Add("(CT.ACTIVESTATUS = 0)");

    if (ddlTaskName.SelectedIndex > 0)
    {
        string strText = ddlTaskName.SelectedItem.Text;
        conditions.Add(String.Format("(CT.ATTR2739 = '{0}')", strText));
    }

    if (ddlService.SelectedIndex > 0)
    {
        string strText = ddlService.SelectedItem.Text;
        conditions.Add(String.Format("(CT.ATTR2846 = '{0}')", strText));
    }

    if (ddlStatus.SelectedIndex > 0)
    {
        string strText = ddlStatus.SelectedItem.Text;
        conditions.Add(String.Format("(CT.ATTR2812 = '{0}')", strText));
    }

    if (ddlDueDate.SelectedIndex > 0)
    {
        string strText = ddlDueDate.SelectedItem.Text;
        conditions.Add(String.Format("(CONVERT(VARCHAR(14), CT.ATTR2752, 110) = '{0}')", strText));
    }

    if (ddlOwner.SelectedIndex > 0)
    {
        string strText = ddlOwner.SelectedItem.Text;
        conditions.Add(String.Format("(UA.REALNAME = '{0}')", strText));
    }

    if (ddlClient.SelectedIndex > 0)
    {
        string strText = ddlClient.SelectedItem.Text;
        conditions.Add(String.Format("(CT.ATTR2799 = '{0}')", strText));
    }

    // You can add additional filters here.  This isn't the cleanest way of doing it, but it's fairly quick and easy as long as you don't intend to add many more filters.

    string conditionsJoined = String.Join(" AND ", conditions);
    string whereClause = String.Format(" WHERE {0}", conditionsJoined);
    return whereClause;
}

这是您的PullData 方法的修改版本。（请注意，我只更改了创建条件语句的顶部。

public void PullData(string sortExp, string sortDir)
{
    string query = String.Format("{0}{1}", strMainQuery, GenerateWhereClause());
    DataTable taskData = new DataTable();
    connString = ""; //the connection string is here

    using (SqlConnection conn = new SqlConnection(connString))
    {
        try
        {
            SqlCommand cmd = new SqlCommand(query, conn);

            // create data adapter
            SqlDataAdapter da = new SqlDataAdapter(query, conn);
            // this will query your database and return the result to your datatable

            DataSet myDataSet = new DataSet();
            da.Fill(myDataSet);

            DataView myDataView = new DataView();
            myDataView = myDataSet.Tables[0].DefaultView;

            if (sortExp != string.Empty)
            {
                myDataView.Sort = string.Format("{0} {1}", sortExp, sortDir);
            }

            yourTasksGV.DataSource = myDataView;
            yourTasksGV.DataBind();

            conn.Close();
        }
        catch (Exception ex)
        {
            string error = ex.Message;
        }
    }
}

【讨论】：

谢谢。一旦我弄清楚如何根据过滤后的 GridView 更改 DropDownList 选项，这就是我打算做的事情。如何根据过滤后的 GridView 过滤 DropDownList？