title: What is a SQL statement to select an item that has several attributes in an item/attribute list?
body: <p>Say I have a table that has items and attributes listed like,</p>
  
  <pre><code>frog    green
  cat     furry
  frog    nice
  cat     4 legs
  frog    4 legs
  </code></pre>
  
  <p>From the items column I want to select unique objects that have both the green and 4 legs attribute. I would expect to get back just the frog object in this case. What is the most efficient query to do this?</p>