title: how to make a column's value match all the values from a subquery
body: <p>How to get the column's values which match all the values from a subquery?</p>
  
  <p>Here my table :</p>
  
  <pre><code>Table P
  p# - pname - color - city
  1  -  nut  -  Red  - London
  2  -  Bolt - Green - Paris
  3  - Screw - Blue  - Rome
  4  - Cam   - Blue  - Paris
  ...
  </code></pre>
  
  <p>For example, if I want the name of the cities which have the same color of piece (P)? </p>
  
  <p>I was thinking about this query:</p>
  
  <pre><code>SELECT city
  FROM P
  WHERE city = 'blue';
  </code></pre>
  
  <p>Of course, it's cheating because I only have a few rows, so how do you write a query that can generalize it ?</p>
  
  <p>*Maybe using EXISTS or NOT EXISTS ?</p>