title: In BIRT, how do I access an arbitrary data set from JavaScript?
body: <p>I am building my first report in <a href="http://www.eclipse.org/birt/phoenix/" rel="nofollow noreferrer">BIRT</a>.</p>
  
  <p>Very quickly I ran into a problem in which I wanted to display some text or data based on an expression that included data from two different tables (not tables that can/should be joined - (hypothetically example- take a student's ACT score from his record in the student table and compare it against the statistics table's entry for ACT statistics).  I soon realized that a data element has to be bound to a dataset (only one of them.) </p>
  
  <p>I found a <a href="http://eclipsezone.net/eclipse/forums/m92006973.html" rel="nofollow noreferrer">similar question</a> in the BIRT mailing list which helped me get to a solution - I can bind an individual data element to a different dataset, but it can still access the elements of its container.  I can send a parameters to the dataset that the element is bound to (e.g. "ACT" in the example I mentioned above).</p>
  
  <p>Eventually however, I came to a place where I needed to use data from three different tables.  I am stuck here, and I'm assuming that there is a way to do this through the scripting abilities, but I have yet to see in the documentation a way to extract data from a data set - everything I have dealt with so far is associated with binding a report element to a dataset.</p>
  
  <p>To be clear, I have seen that I can add JavaScript functions to the initialize section of the top level report (and call them from an expression in a data element) but I don't see how in a script I can query any of my datasets -- as opposed to only interacting with the dataset bound to my data element).</p>
  
  <p>How can I access an arbitrary (though already defined) data set from JavaScript in BIRT?  (Or how can I access more than two datasets from an element - one that it is bound to, and one that its container is bound to?)</p>