Question

I have two tables:

Topic (   TopicID: int, (primary key)   TopicName: varchar );  Example (   ExampleID: int, (primary key)   TopicID: int, (foreign key to Topic table)   ExampleOrder: int,   ExampleName: varchar ); 

Using Linq, given an ExampleID, I want to get the next example in the same topic (with the same TopicID). Here’s how it might be done in sql:

DECLARE @ExampleOrder int; DECLARE @TopicID int; SELECT @ExampleOrder=ExampleOrder, @TopicID=TopicID FROM Example WHERE ExampleID=@ExampleID; SELECT TOP 1 ExampleID FROM Example WHERE TopicID=@TopicID AND ExampleOrder>@ExampleOrder ORDER BY ExampleOrder 

Is there a simple way to do this in Linq? I know I can do this with two Linq queries, but I’m trying to get it done without extra round trips to the database.

Answer 1

int exampleID = 5;   //now to write a query var query =   from ex in db.Examples   let prior = db.Examples.Where(ex2 => ex2.ExampleID == exampleID).First()   where ex.TopicID == prior.TopicID      && ex.ExampleOrder > prior.ExampleOrder   order ex by ex.ExampleOrder descending   select ex     //ok, let's run the query - result will have 0 or 1 item in it. List<Example> result = query.Take(1).ToList();