title: i cannot understand the code e1.sal <= e2.sal
body: <pre><code>select distinct salary 
  from downtodate1.employe AS e1 
  where 3 = (
      select count(distinct salary) 
      from downtodate1.employe e2 
      where **e1.salary &lt;= e2.salary**
  );
  </code></pre>
  
  <p>Please explain the line </p>
  
  <pre><code>e1.salary &lt;= e2.salary
  </code></pre>