title: Any good examples/references implementing ACLs via SQL?
body: <p>I currently have a web-application that implements a rudimentary form of ACL using UNIONs in mysql, but it's somewhat limited, and doesn't necessarily scale that well</p>
  
  <p>I'm interested in any alternative ACL algorithms that could be implemented efficiently in SQL.  </p>
  
  <p>Thanks!</p>