How can you handle an IN sub-query with LINQ to SQL?

Question

I'm a bit stuck on this. Basically I want to do something like the following SQL query in LINQ to SQL:

SELECT f.* 
FROM Foo f
WHERE f.FooId IN (
    SELECT fb.FooId
    FROM FooBar fb
    WHERE fb.BarId = 1000
)

Any help would be gratefully received.

Answer 1

General way to implement IN in LINQ to SQL

var q = from t1 in table1
        let t2s = from t2 in table2
                  where <Conditions for table2>
                  select t2.KeyField
        where t2s.Contains(t1.KeyField)
        select t1;

General way to implement EXISTS in LINQ to SQL

var q = from t1 in table1
        let t2s = from t2 in table2
                  where <Conditions for table2>
                  select t2.KeyField
        where t2s.Any(t1.KeyField)
        select t1;