title: SQL query - Find all couples of actors who has played EXACTLY in the same movies
body: <p>I am practicing for the database exam I have shortly but I can't figure out how to make this query. </p>
  
  <p>I copy paste the excercise as it is:
  Given 2 tables</p>
  
  <pre><code>FILM(Title, Director, Year, Genre)
  InCastOf(Actor, Film) Where InCastOf(film) is constrained to Film(Title)
  </code></pre>
  
  <p>Write a query to find all couples of actors who have played EXACTLY in the same movies.</p>
  
  <p>What I got so far is:</p>
  
  <pre><code>SELECT InCastOf.Actor AS A1, T.Actor AS A2, InCastOf.Film FROM InCastOf
  JOIN (SELECT Actor, Film FROM InCastOf) AS T ON InCastOf.Film = T.Film
  WHERE  InCastOf.Actor != T.Actor
  </code></pre>
  
  <p>Which returns me for each film a pair of actors who played in it. I could use group by etc to nail down the query, but the word "Exactly" is causing me some trouble because I need to make sure those actors only worked on the same movies and nothing else. At least that is what I understand from the word "Exactly". </p>
  
  <p>Thanks for the help! </p>