GridView不能删除值asp.net

Question

protected void Page_Load(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    string VisitorManagementConnectionString = ConfigurationManager.ConnectionStrings["VisitorManagementConnectionString"].ConnectionString;
    string strQuery = "select Id, ItemName, FoundAt, TimeIn, ImageName from LostFound order by ID";
    SqlCommand cmd = new SqlCommand(strQuery);
    SqlConnection con = new SqlConnection(VisitorManagementConnectionString);
    SqlDataAdapter sda = new SqlDataAdapter();
    cmd.CommandType = CommandType.Text;
    cmd.Connection = con;
    ViewState["dt"] = dt;
    BindGrid();
    try
    {
        con.Open();
        sda.SelectCommand = cmd;
        sda.Fill(dt);
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
    catch (Exception ex)
    {
        Response.Write(ex.Message);
    }
    finally
    {
        con.Close();
        sda.Dispose();
        con.Dispose();
        dt.Dispose(); 

    } 
}
protected void BindGrid()
{
    GridView1.DataSource = ViewState["dt"] as DataTable;
    GridView1.DataBind();
}
protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{

}
protected void BtnLose_Click(object sender, EventArgs e)
{
    Response.Redirect("SecurityLost.aspx");
}

protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        string ID = e.Row.Cells[0].Text;
        foreach (Button button in e.Row.Cells[5].Controls.OfType<Button>())
        {
            if (button.CommandName == "Delete")
            {
                button.Attributes["onclick"] = "if(!confirm('Do you want to delete " + ID + "?')){ return false; };";
            }
        }
    }
}

protected void OnRowDeleting(object sender, GridViewDeleteEventArgs e)
{
    int ID = Convert.ToInt32(e.RowIndex);
    DataTable dt = ViewState["dt"] as DataTable;
    dt.Rows[ID].Delete();
    string VisitorManagementConnectionString = ConfigurationManager.ConnectionStrings["VisitorManagementConnectionString"].ConnectionString;
    using (SqlConnection con = new SqlConnection(VisitorManagementConnectionString))
    {
        using (SqlCommand cmd = new SqlCommand("DELETE FROM LostFound WHERE ID = @ID"))
        {
            cmd.Parameters.AddWithValue("@ID", ID);
            cmd.Connection = con;
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }
    BindGrid();
}

when i press delete button the row can be delete but when i reload the page the row i deleted still appeal back and my database also never be deleted.

Can someone guide me where am I going wrong?

          <asp:GridView ID="GridView1" runat="server" OnRowDataBound = "OnRowDataBound" AutoGenerateColumns = "false" OnRowDeleting="OnRowDeleting" Font-Names = "Arial" Caption = "Lose & Found" OnSelectedIndexChanged="GridView1_SelectedIndexChanged">
            <Columns>
                <asp:BoundField DataField = "ID" HeaderText = "ID" />
                 <asp:BoundField DataField = "ItemName" HeaderText = "Item Name" />
                <asp:BoundField DataField = "FoundAt" HeaderText = "Place" />
                <asp:BoundField DataField = "TimeIn" HeaderText = "Time Found" />
                <asp:ImageField DataImageUrlField = "ID" DataImageUrlFormatString = "Image.aspx?ImageID={0}" ControlStyle-Width = "100" ControlStyle-Height = "100" HeaderText = "Preview Image"/>
                <asp:CommandField ShowDeleteButton="True" ButtonType="Button" />
            </Columns> 
         </asp:GridView>

This my HTML file.

Answer 1

So from the comments we've established that the problem is that your ID is always 0.To make sure the ID comes through correctly you need to make two changes:

1.Change the Page_Load() event like this:

protected void Page_Load(object sender, EventArgs e)
{
    if(!Page.IsPostBack)
    {
        //Cut and paste the code to bind to the GridView here
    }
}

2.Add this code to the RowDeleting event:

protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
    int id = Int32.Parse(GridView1.Rows[e.RowIndex].Cells[0].Text);
}