Row delete from database or Viewstate/Datatable

Question

i have gridview,i want condition to delete row from gridview,

<asp:GridView ID="GridView1" runat="server" AllowSorting="True" HorizontalAlign="Center" AutoGenerateColumns="false" CssClass="mygrdContent" HeaderStyle-BackColor="#66ccff" HeaderStyle-CssClass="header" HeaderStyle-ForeColor="White" OnRowDataBound="GridView1_RowDataBound" OnRowDeleting="GridView1_RowDeleting" PagerStyle-CssClass="pager" RowStyle-CssClass="rows" Width="452px" ShowFooter="True">
<Columns>
<asp:TemplateField HeaderText="ID">
<ItemTemplate>
<asp:Label ID="D_CID" runat="server" Text='<%#Bind("D_CID")%>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Container">
<ItemTemplate>
<asp:Label ID="Contnam" runat="server" Text='<%#Bind("Contnam")%>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="QTY">
<ItemTemplate>
<asp:Label ID="QTY" runat="server" Text='<%#Bind("QTY")%>'></asp:Label>
</ItemTemplate>
<FooterTemplate>
<asp:Label ID="lblTotal1" runat="server"></asp:Label>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
</ItemTemplate>
<EditItemTemplate>
</EditItemTemplate>
</asp:TemplateField>
<asp:CommandField ButtonType="Button" ShowDeleteButton="True" />
</Columns>
<HeaderStyle BackColor="#66CCFF" ForeColor="White" />
<SelectedRowStyle BackColor="Yellow" />
</asp:GridView>

if i have data in gridview in datatable/Viewstate then it delete from viewstate if first column id does not exit ,

if i have ID in first column ,which i retrieved from database then it deleted from database below i tried but it is not working

protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
int id = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Value);
int index = Convert.ToInt32(e.RowIndex);
DataTable dt = (DataTable)ViewState["dt"];
// Delete from ViewState.
dt.Rows[index].Delete();
ViewState["dt"] = dt;
string query = "delete from tbl_Import_Detail WHERE D_CID = @Id";
using (SqlCommand cmd = new SqlCommand(query))
{
cmd.Connection = con;
cmd.Parameters.AddWithValue("@Id", id);
con.Open();
cmd.ExecuteNonQuery();
con.Close();
}
BindGridView();