嵌套WHERE IN子句SQL到LINQ

Question

I have a nested WHERE IN clause in my SQL, how would this translate to LINQ, bonus points for using lambda expressions. New to all of this.

SELECT EndowmentID
  FROM Criteria c
 WHERE c.ID IN(

       SELECT CriterionID
         FROM Filters
        WHERE ChoiceID IN(

              SELECT ChoiceID
                FROM Responses
               WHERE ApplicationID = 1

              )

       )

Answer 1

This query can definitely be improved using joins...

SELECT EndowmentID
FROM
    Criteria C
    JOIN Filters F ON C.ID = F.CriterionID
    JOIN Responses R ON F.ChoiceID = R.ChoiceID
WHERE R.ApplicationID = 1

Depending on the keys of your tables you might have to SELECT DISTINCT

From there you can write a simple LINQ query:

from c in Criteria
join f in Filters on c.ID equals f.CriterionID
join r in Responses on f.ChoiceID equals r.ChoiceID
where r.ApplicationID = 1
select c.EndowmentID

Again, you might have to Distinct() this.

Answer 2

var result =
    Criteria.Where(c => 
        Filters.Where(f =>       
            Responses.Where(r => r.ApplicationId == 1).Select(r => r.ChoiceId)
                .Contains(f.ChoiceId)
        ).Select(f => f.CriterionId)
        .Contains(c.Id)
     ).Select(c => EndowmentId);