title: SQL query to find at least one solution
body: <p>I have a bunch of table, say, Job and transactions</p>
  
  <pre><code>Job:
  
  id   Name
  4    Clay
  6    Glow
  7    Circle
  9    Jam
  
  Transactions
  
  Id   Job_id      Person     Marks
  2     6           Amy        0
  3     3           Keith      30
  5     3           Glass       10
  7     9           Know       60
  11    6           Play       81
  13    6           Play       100
  </code></pre>
  
  <p>How do I find below return query which should return three column Job_id(Id of Job), Job_name(name of job) and level , which is one of three possible Strings: "Hard", "Easy", "Medium".</p>
  
  <pre><code>   **Job_id**       **Job_name**      **Level**
  ----------------------------------------------------
         4                Clay           Hard
         6                Glow           Easy
         9                Jam            Medium
  </code></pre>
  
  <p>Level is calculated if average score on Transactions, 
  -- If average score for job is lower than or equal to 20, then its level is "Hard".
  -- If average score for job is higher than 20 but lower than or equal to 60, then its level is "Medium".
  -- If average score for job is higher than 60, then its level is "Easy".</p>
  
  <p>I'm not sure if I should use a subQuery for this, or if there's an easier way.</p>
  
  <p>Thanks!</p>