Is pure SQL available for Linq to SQL?

Question

Is pure (or should I say that it works) SQL reachable in Linq to Sql?

I wanted Linq to Sql to output this code:

SELECT C.CustomerID, COUNT(O.CustomerID) AS N
FROM Customers C
LEFT JOIN Orders O ON O.CustomerID = C.CustomerID
GROUP BY C.CustomerID

And I follow this code: LINQ - Left Join, Group By and Count

So here is my version of the code:

var q = from c in db.Customers
        join o in db.Orders on c.CustomerID equals o.CustomerID into sr
        from x in sr.DefaultIfEmpty()
        group x by c.CustomerID into y
        select new { y.Key, N = y.Count(t => t.CustomerID != null) };

But he generates it ...

SELECT [t2].[CustomerID] AS [Key], (
    SELECT COUNT(*)
    FROM [Customers] AS [t3]
    LEFT OUTER JOIN [Orders] AS [t4] ON [t3].[CustomerID] = [t4].[CustomerID]
    WHERE ([t4].[CustomerID] IS NOT NULL) AND ((([t2].[CustomerID] IS NULL) AND ([t3].[CustomerID] IS NULL)) OR (([t2].[CustomerID] IS NOT NULL) AND ([t3].[CustomerID] IS NOT NULL) AND ([t2].[CustomerID] = [t3].[CustomerID])))
    ) AS [N]
FROM (
    SELECT [t0].[CustomerID]
    FROM [Customers] AS [t0]
    LEFT OUTER JOIN [Orders] AS [t1] ON [t0].[CustomerID] = [t1].[CustomerID]
    GROUP BY [t0].[CustomerID]
    ) AS [t2]

... which I find unacceptable.

Then I will try this ...

var q = from c in db.Customers
        join o in db.Orders on c.CustomerID equals o.CustomerID into sr
        from x in sr.DefaultIfEmpty()
        group x by c.CustomerID into y                                        
        select new { y.Key, N = y.Sum(t => t.CustomerID != null ? 1 : 0 )};

... and here is the resulting query:

SELECT SUM(
    (CASE
        WHEN [t1].[CustomerID] IS NOT NULL THEN @p0
        ELSE @p1
     END)) AS [N], [t0].[CustomerID] AS [Key]
FROM [Customers] AS [t0]
LEFT OUTER JOIN [Orders] AS [t1] ON [t0].[CustomerID] = [t1].[CustomerID]
GROUP BY [t0].[CustomerID]

Although a little cleaner and looks fulfilled, it is still not so succinct and effective compared to the simpler statement: COUNT(O.CustomerID)

Am I trying to do this in Linq for SQL?

What about other ORMs? in particular NHibernate, can it translate the HQL statement into its real SQL?

Answer 1

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