title: How do you return only groups that contain a specific value in MySQL?
body: <p>Given a table <code>mytable</code> with 2 columns like</p>
  <pre><code>|   foo   |  bar    | 
  |   a     |   10    | 
  |   b     |   10    |   
  |   b     |   15    | 
  |   c     |   10    | 
  |   c     |   10    | 
  |   c     |   10    |  
  |   d     |   10    | 
  |   d     |   45    |  
  |   e     |   20    | 
  </code></pre>
  <p>How I return the groups of <code>foo</code> that <em>only</em> contain the value <code>10</code>?</p>
  <p>The resulting dataset for the above should look like</p>
  <pre><code>|   foo   |  bar    | 
  |   a     |   10    |  
  |   c     |   10    |  
  </code></pre>
  <p>Note that b and d do not get returned because 15 and 45 are also values in those groups.</p>