How to translate an advanced SQL statement with LEFT OUTER JOIN to LINQ? - linq-to-sql

Question

I have a similar SQL statement as shown in this example. For the following table
CREATE TABLE [docs] (
[id] int NOT NULL,
[rev] int NOT NULL,
[content] varchar(200) NOT NULL,
PRIMARY KEY ([id],[rev])
) ;
and the following data
INSERT INTO [docs] ([id], [rev], [content]) VALUES
(1, 1, 'The earth is flat'),
(2, 1, 'One hundred angels can dance on the head of a pin'),
(1, 2, 'The earth is flat and rests on a bull``s horn'),
(1, 3, 'The earth is like a ball.');
the SQL statement
SELECT d1.*
FROM docs AS d1
LEFT OUTER JOIN docs AS d2
ON (d1.id = d2.id AND d1.rev < d2.rev)
WHERE d2.id is null
ORDER BY id;
shows only rows with maximum rev value for each id:
id rev content
1 3 The earth is like a ball.
2 1 One hundred angels can dance on the head of a pin
My question:
How can I translate this statement to LINQ-to-SQL? The problem in my point of view are the AND and the < in the ON clause.

Answer 1

In general, it is best to translate a SQL LEFT JOIN...WHERE ... = null into an EXISTS which in LINQ is Any:
var ans = from d1 in docs
join d2 in docs on d1.id equals d2.id into d2j
where !d2j.Any(d2 => d1.rev < d2.rev)
orderby d1.id
select d1;
But, of course, you can translate it into an explicit LINQ null test:
using (MyDataContext context = new MyDataContext()) {
var query =
from d1 in context.docs
join d2 in context.docs on d1.id equals d2.id into d2j
from d2 in d2j.Where(d2_2 => d1.rev < d2_2.rev).DefaultIfEmpty()
where d2 == null
select d1;
return query.ToArray();
}

Answer 2

I tried to apply #NetMage's recipe but I got stuck at the < condition:
using (MyDataContext context = new MyDataContext())
{
var query =
from d1 in context.docs
join d2 in context.docs on d1.id equals d2.id into jrv
from x in jrv.Where(x => /* ??? */).DefaultIfEmpty()
where x equals null
select x;
return query.ToArray();
}
The lambda expression in Where should be a comparison between d1.rev and d2.rev. How can I do that?