linq - Linq の内部クエリ

Question

ユーザーが以前に試みたことのない、質問テーブルから質問を取得する linq クエリを作成する方法。

質問表

create table questions
(
  questionID int,
  question varchar,
  primary key(questionID)
);

create table result
{
  id int,
  answered_by varchar,
  questionid int,
  answer varchar,
  primary key (id),
  foreign key ( questionid) references question(questionID)
);

Answer 1

from QUESTION in QUESTIONS
join
ANSWER in RESULT
on
QUESTION.questionID equlas ANSWER.questionid
where
ANSWER.answer!=NULL
select {QUESTION.questionID, ANSWER.answered_by, ANSWER.questionid, ANSWER.answer}