Linq null value

hi there
i have this query :

var result2 = (from TH in DB.Threshold
                          where TH.ProductSKUID == int.Parse(HID_ProductSKUID.Value)
                          select TH.ThresholdID).Max();

the problem is that if this query does not find any items, return null, so thow exception
how can i do to return 0??

I have a linq to sql entity class in which I declared some DateTime fileds like this:

[Column(DbType = "smalldatetime")]
public DateTime? StartDate { get; set; }

And this is how I fetch data form repository:

return repository.Logs.OrderByDescending(l => l.LogID).FirstOrDefault();

All non DateTime fields are filled properly but all datetimes are null.

I am converting my datatable to LISt using LINQ
how do I handle nulls coming from database

List<Port> portDetails = new List<Port>();
DataTable dt = ds.Tables[0];               
portDetails = (from q in dt.AsEnumerable()
select new Port
{
PortCode = q.Field<string>("Code"),
ExtCode = q.Field<string>("Nb"),
Name = q.Field<string>("Name"))
}).ToList(); 

In the above query if Code is null I do not want property
portcode to be set to the value it should only set if it is
not null or not blank 
PortCode = q.Field<string>("Code"),

What should be syntax
I was trying somethign like this which doesnt work
Portcode = q.Field<bool>("Code") == null ? null : q.Field<bool>("Code")

from e in Employees
where e.EmployeeID == id
select new {
Sales1 = e.HomeSales.Max(),
Sales2 = e.AwaySales.Max()};

I have to get the maximum of these two select values. The select values are nullable. How do I go about checking if the value is null before 
calling the Max() method on it? 

I tried the ?? coalesing operator (example: e.HomeSales.Max() ?? 0M,) but I get the following error:

"Operator '??' cannot be applied to operands of type 'decimal' and 'decimal'"

I've got a web service that returns xml from a linq query.

If i have fields 'name' and 'title' my linq query will return results that have data in both 'name and 'title' fields.

How can I get linq to return a query when both fields are populated, and when only the name field contains data?

Here's what I've got:

        [WebMethod]
        public XmlDocument GetUsersByDate()
        {
            StringBuilder sb = new StringBuilder();
            XmlWriter writer = XmlWriter.Create(sb);

            var SelectedUsers = (from u in db.Users
                                 select "<UserName>" + u.UserName + "</UserName><x>" + u.Title + "<x>").ToList();

            writer.WriteStartDocument();
  &

I'm creating my first xml file via linq to xml however I'm encountering an issue.  I need to be able to exclude a set of elements when a certain element is NULL.

My xml file contains info on customer orders.  If the customer entered their phone number info, then there are several xml elements that need to be filled in (phone number, number type, phone extension, etc).  If they left their phone number blank however, then the xml elements should be suppressed.

So the xml should either look like this:

---------------------------------------------------

<phone>

   <phonenumber>555-555-5555</phonenumber>

   <numbertype>mobile</numbertype>

</phone