Need help building SQL Query (simple JOIN)

In my database, I have a "users", a "quests" and a "questings" table. A user can solve a quest. Solving a quest will save the "user_id" and the "quest_id" in my "questings" table.

Now, I want to select all quests, a user has NOT solved (meanin开发者_Python百科g there is no entry for this user and quest in "questings" table)!

Let's say the user has the id 14. How to write this query?

After solving this query, I want to filter the results, too. A quest and a user has a city, too. What to do for writing a query which returns all quests, a user has NOT solved yet, in the users city (user city == quest city)?

SELECT *
  FROM Quests
 WHERE Quest_ID NOT IN (
       SELECT DISTINCT(Quest_ID)
         FROM Questing
        WHERE User_ID = 14)

select * from quests q, users u
  where u.id = 14 AND q.city=u.city AND 
          q.id not in ( select DISTINCT(quest_id) from questing );