title: SQL query for finding pairs that share the exact same set of values
body: <p>I'm having trouble generating a query for this problem.</p>
  
  <p>I have this small table</p>
  
  <pre><code>Tasks(employee_name, task)
  
  Sample Data:
  Tasks
  ------------------
  Joe | taskA
  Joe | taskB
  Ted | taskA
  Jim | taskB
  Ray | taskA
  Ray | taskB
  John| taskA
  Tim | taskC
  </code></pre>
  
  <p>I need to find all pairs of employees that have the exact same tasks.</p>
  
  <p>For example using the data above the result set should be:</p>
  
  <pre><code>---------------------
  employee1 | employee2
  ---------------------
    Joe     | Ray
    Ted     | John
  </code></pre>
  
  <p>I'm using mySQL for the database.
  Thanks!</p>