title: Constraint, based on join with another table
body: <p>I have table <code>tariffs</code>, with two columns: <code>(tariff_id, reception)</code></p>
  
  <p>I have table <code>users</code>, with two columns: <code>(user_id, reception)</code></p>
  
  <p>And I have table <code>users_tariffs</code> with two columns: <code>(user_id, tariff_id)</code>.</p>
  
  <p>I want to prevent situation when tariff from one reception is assigned to user from another reception. How can I do that?</p>
  
  <p>E.G</p>
  
  <p>Users:</p>
  
  <pre><code>user_id | reception
  Putin   | Russia
  Trump   | USA
  </code></pre>
  
  <p>Tariffs:</p>
  
  <pre><code>tariff_id | reception
  cheap     | USA
  expensive | Russia
  </code></pre>
  
  <p>Wrong situation at users_tariffs, because Cheap tariff is for USA only:</p>
  
  <pre><code>user_id | tariff_id
  Putin   | Cheap
  </code></pre>