title: Populate second table with averages from first
body: <p>I've got two tables, <em>transactions</em> and <em>listings</em>.</p>
  
  <p><em>transactions</em> list all of my transactions that occur each day. I have a column in transactions that lists the price of each transacted item. Several transactions occur each day. I would like to take the median or mean of all transactions in each day, and populate a new column in <em>listings</em> with this information.</p>
  
  <p>So my end result would have a column in <em>listings</em> called daily_price_average, that takes the average price of individual transaction information from <em>transactions</em>.</p>
  
  <p>Any thoughts on how to do this?</p>
  
  <p>Or how could I do this using a view?</p>