private bool check_ma_ok(DataTable ip_dt, string ma)
{
var list_ma = (from DataRow dr in ip_dt.Rows
where dr[1] != null
select dr[1]).ToList();
foreach (var item in list_ma)
{
if (String.IsNullOrEmpty(item.ToString()))
{
continue;
}
if (item.ToString() == ma)
{
return true;
}
}
return false;
}