title: sql: selecting specific data concerning two different tables
body: <p>So here's the situation, I made two tables:</p>
  
  <p>table 1:</p>
  
  <pre><code>create table Show (
      id number(5),
      moderator_id number(5),
      length number(3),      
      title varchar(100),
      details varchar(30)
  );  
  </code></pre>
  
  <p>table 2:             </p>
  
  <pre><code>create table Moderator (
      id number(5),
      name varchar(30),
      surname varchar(30)
  );
  </code></pre>
  
  <p>The two tables are in relation: 1(Moderator), N(Show) 
  I need a command, that displays name and surname of moderator, that haves the biggest SUM of length (Show.length represents length of individual show).</p>