if (GV.DataSource == null)
{
//DataGridViewRow row = GV.Rows.Cast<DataGridViewRow>().FirstOrDefault(rd => rd.Cells[0].EditedFormattedValue.Equals(dt.Rows[i]["IDCardNum"].ToString()));
//if (row != null) GV.Rows.Remove(row);
sesstab.Rows.InsertAt(dr, 0);
}
else
{
DataTable dd = (DataTable)GV.DataSource;
DataRow row = dd.Rows.Cast<DataRow>().FirstOrDefault(rd => rd[0].Equals(dt.Rows[i]["IDCardNum"].ToString()));
if (row != null) dd.Rows.Remove(row);
sesstab.Rows.InsertAt(dr, 0);
}