Try this... :-)
foreach (DataRow dr in dtTotal.Rows)
{
string Schedule_Date_For_GFC = dr["Schedule_Date_For_GFC"].ToString();
DateTime d;
if (DateTime.TryParse(Schedule_Date_For_GFC, out d))
{
Schedule_Date_For_GFC = d.ToString("yy-MMM-yyyy");
}
else
{
}
}
You see this basically parses the current value of your string into a DateTime, which is then used to change your string into the format you want.
Hope this helps...