How to detemine if sequence has items and if so return the value in LINQ

I currently do a lot of checks like so

If (From p In table Where p.USER_ID = LoggedInUser.USER_ID And p.DATE >= start And p.DATE < [end] And p.PR开发者_如何学COJECT_ID = ProjectId Select p.Field).Any Then
                Me.lblOverallTotal.Text = (From p In table Where p.USER_ID = LoggedInUser.USER_ID And p.DATE >= start And p.DATE < [end] And p.PROJECT_ID = ProjectId Select p.Field).Sum.ToString
            Else
                Me.lblOverallTotal.Text = "0.0"
            End If

however this results in two db hits. (one to determine if any and then one to calculate the sum.

I am sure there must be a less verbose method to do this but am struggling to find the synta

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I would do something like (switching to C# as my VB is weak):

var sum = (from p in table
           where p.USER_ID == LoggedInUser.USER_ID
           && p.DATE >= start
           && p.DATE < end
           && p.PROJECT_ID == ProjectId 
           select (float?)p.Field).Sum(); // use the correct data type here

LINQ-to-SQL (courtesy of SQL-server) has a foible where that gives null if there are no results, i.e.

 Me.lblOverallTotal.Text = (sum ?? 0).ToString();

The key point there (for reading it as VB): switch to Nullable-of-the-type and Sum() it. Then compare to null.