gistfile1.fs

query {
    for p in queryable<Person>() do
    where(query {
        for e in queryable<Employee>() do
        where(e.DepartmentId = Some(!departmentId))
        select e.PersonId
        contains p.PersonId
    })
    select p
}

gistfile2.sql

SELECT T.PersonId
	,T.PersonName
	,T.JobKind
	,T.VersionNo
FROM Person AS T
WHERE (
		T.PersonId IN (
			SELECT T2.PersonId
			FROM Employee AS T2
			WHERE (T2.DepartmentId = @p1)
			)
		)