Question

I have a need to create a LINQ query that returns results based on a subquery. Not quite sure I’m wording that properly but the best way I know to ask is to show an example. How can I turn the following TSQL query into a LINQ query (tables are same name as objects):

SELECT CuisineId, Name 
FROM Cuisine 
WHERE CuisineId NOT IN (SELECT CuisineId 
                        FROM RestaurantCuisine 
                        WHERE RestaurantId = @id)

As you can guess, I’m trying to get a list of “available” cuisines to be listed for a user to add to a list of cuisines that a restaurant offers. The LINQ I have thus far returns ALL cuisines and doesn’t take in account of the existing CuisineId’s that have already been added to the other table:

I’ve looked all over for an example but not quite sure how to describe exactly what I need. I looked at the MSDN reference for LINQ queries but couldn’t find anything like what I need:

MSDN LINQ Sample Queries

Anyone able to give me an example?

Answer 1

In C#:

var query =
    from c in db.Cuisine

    where !(from rc in db.RestaurantCuisine
            where rc.RestaurantId == id
            select rc.CuisineId)
          .Contains(c.CuisineId)

    select new {
        c.CuisineId,
        c.Name
    };

In VB.NET:

Dim availableCuisines = _
    From c In db.Cuisines _
    Where Not (From rc In db.RestaurantCuisines _
               Where rc.RestaurantId = id _
               Select rc.CuisineId) _
              .Contains(c.CuisineId) _
    Select c