During ascending sort blank rows coming earlier issue in ASP.NET C# Gridview

I am trying to view/add/update/delete records with textboxes in same gridview. Only save button will be there at the end of page.

I have an ASP.NET gridview with 5 textboxes in every row. Page size of gridview is 20 records on each page. I have enabled sorting on every column. When the gridview is getting populated, then we are getting 28 filled records and 12 empty records.

When I hit sorting in asc mode on any column, it shows the blank rows earlier than the records with data. I want to ignore those blank records while sorting.

I tried using a custom onsorting method on gridview but it’s not working.

aspx code

 <asp:GridView runat="server" ID="gvDetails" AllowPaging="true" PageSize="20" Allow AutoGenerateColumns="false" DataKeyNames="ProdId" OnPageIndexChanging="gvDetails_PageIndexChanging" OnSorting="gvDetails_OnSorting">
<HeaderStyle CssClass="headerstyle" />
<Columns>
<asp:TemplateField HeaderText="Product Name" SortExpression="ProdName">
<ItemTemplate>
<asp:TextBox ID="txtProductName" runat="server" Text='<%# Eval("ProdName") %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Description" SortExpression="ProdDesc">
<ItemTemplate>
<asp:TextBox ID="txtProdDesc" runat="server" Text='<%# Eval("ProdDesc") %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Price" SortExpression="ProdPrice">
<ItemTemplate>
<asp:TextBox ID="txtProdPrice" runat="server" Text='<%# Eval("ProdPrice") %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Category" SortExpression="ProdCat">
<ItemTemplate>
<asp:TextBox ID="txtProdCat" runat="server" Text='<%# Eval("ProdCat") %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Delete">
<ItemTemplate>
<asp:CheckBox ID="chkDelete" runat="server" Checked='<%# Eval("IsDelete") %>' />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
BindGridview();
}
}

protected DataTable BindGridview()
{
DataSet ds = new DataSet();
using (SqlConnection con = new SqlConnection("#"))
{
con.Open();
SqlCommand cmd = new SqlCommand("crudoperations", con);
cmd.CommandType= CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("@status","SELECT");
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(ds);
con.Close();
if (ds.Tables[0].Rows.Count > 0)
{
gvDetails.DataSource = ds;
gvDetails.DataBind();
}
else {
ds.Tables[0].Rows.Add(ds.Tables[0].NewRow());
gvDetails.DataSource = ds;
gvDetails.DataBind();
int columncount = gvDetails.Rows[0].Cells.Count;
gvDetails.Rows[0].Cells.Clear();
gvDetails.Rows[0].Cells.Add(new TableCell());
gvDetails.Rows[0].Cells[0].ColumnSpan = columncount;
gvDetails.Rows[0].Cells[0].Text = "No Records Found";
}
}
return ds.Tables[0];
}

 public void gvDetails_OnSorting(Object sender, GridViewSortEventArgs e)
{
string sortingDirection = string.Empty;  
if (direction == SortDirection.Ascending)  
{  
direction = SortDirection.Descending;  
sortingDirection = "Desc";  
  
}  
else  
{  
direction = SortDirection.Ascending;  
sortingDirection = "Asc";  
  
}  
DataView sortedView = new DataView(BindGridView());  
sortedView.Sort = e.SortExpression + " " + sortingDirection;  
gvDetails.DataSource = sortedView;  
gvDetails.DataBind();  
}