select memname,
      CONVERT(nvarchar, DATEDIFF(d,CompleteDate,FreeTrialTaskMst.Enddate)) AS Difference
  from member

<asp:TemplateField HeaderText=" DeadLine">
     <ItemTemplate>
     <asp:Label ID="lblDeadLine" runat="server" Text='<%# (Eval("DeadLine")) %>' ReadOnly="true"></asp:Label>
    </ItemTemplate>
   </asp:TemplateField>

select memname,
    (case when  DATEDIFF(d,CompleteDate,FreeTrialTaskMst.Enddate) >0 then 'completed'
else 'Not Complete' end) as  DeadLine
  from member

protected void gridview1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        DataRow row = ((DataRowView)e.Row.DataItem).Row;
        Label lblDeadLine = (Label)e.Row.FindControl("lblDeadLine");
        int deadLine = int.Parse(row.Field<String>("DeadLine"));
        if(deadLine < 0)
            lblDeadLine.Text = "Not Completed in Time";
        else
            lblDeadLine.Text = "Completed in Time";
    }
}