Question

我在C＃中运行的两个查询是在datagridview中运行的，一个是显示所有数据。另一个设置为在页脚中显示。页脚显示，只是不显示我的查询。 查询一个（带页脚）

protected void Button2_Click(object sender, EventArgs e)
{
   MySqlCommand cmd = new MySqlCommand("SELECT * FROM Customer", cs);
   cs.Open();
   MySqlDataReader dgl = cmd.ExecuteReader();
   dg.ShowFooter = true;
   dg.DataSource = dgl;
   dg.DataBind();
   cs.Close();
}
**query two(footer query)**
protected void dg_DataBound(object sender, EventArgs e)
{
   MySqlCommand cmd = new MySqlCommand("SELECT SUM(Donation) AS Total_Donation FROM Customer", cs);
   cs.Open();
   String totalDonations = Convert.ToString(cmd.ExecuteScalar());
   cs.Close();
   dg.FooterRow.Cells[3].Text = totalDonations;
}

数据网格显示查询效果良好，页脚甚至显示但没有任何数据。

Answer 1

经过几个小时的问题，我已经解决了。

corrected code


{
        MySqlCommand cmd = new MySqlCommand("SELECT * FROM Customer", cs);
        MySqlCommand cmdtwo = new MySqlCommand("SELECT SUM(Donation) AS Total_Donation FROM Customer", cs);
        cs.Open();
        MySqlDataReader dgl = cmd.ExecuteReader();
        dg.DataSource = dgl;
        dg.ShowFooter = true;
        dg.DataBind();
        cs.Close();
        cs.Open();
        string totalDonations = Convert.ToString(cmdtwo.ExecuteScalar());
        cs.Close();
        dg.FooterRow.Cells[7].Text = "Total £";
        dg.FooterRow.Cells[8].Text = totalDonations;
}

虽然我确信有更好的方法可以做到这一点，如果您知道，请随时编辑。

Answer 2

虽然你有它的工作方式，但仍有办法改进它。

在第一种方法中，using语句可以更好地管理连接：

protected void Button2_Click(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    //Assuming you have a connection string strConnect
    using (SqlConnection con = new SqlConnection(strConnect))
    {
        con.Open();
        using (SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM Customer", con))
        {
            da.Fill(dt);
        }
    }
    dg.ShowFooter = true;
    dg.DataSource = dt;
    dg.DataBind();
}

第二种方法：

protected void dg_DataBound(object sender, EventArgs e)
{
    String totalDonations = string.Empty;
    //Assuming you have a connection string strConnect
    using (SqlConnection con = new SqlConnection(strConnect))
    {
        con.Open();
        using (SqlCommand cmd = new SqlCommand("SELECT SUM(Donation) AS Total_Donation FROM Customer", con))
        {
            totalDonations = Convert.ToString(cmd.ExecuteScalar());
        }
    }

    dg.FooterRow.Cells[3].Text = totalDonations;
}

我可能会使用GridView的RowDataBound写入页脚，我可以知道行的类型：

protected void dg_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.Footer)
    {
        String totalDonations = string.Empty;
        //Assuming you have a connection string strConnect
        using (SqlConnection con = new SqlConnection(strConnect))
        {
            con.Open();
            using (SqlCommand cmd = new SqlCommand("SELECT SUM(Donation) AS Total_Donation FROM Customer", con))
            {
                totalDonations = Convert.ToString(cmd.ExecuteScalar());
            }
        }
        e.Row.Cells[3].Text = totalDonations;
    }
}

编辑：以下是我用来测试的标记：

<asp:GridView ID="dg" runat="server" AutoGenerateColumns="true" OnDataBound="dg_DataBound" ShowFooter="true"> 
</asp:GridView>

webform中的datagridview c＃在页脚中显示查询

2 个答案: