title: Amazon Athena LEFT OUTER JOIN query not working as expected
body: <p>I am trying to do a left ourter join in Athena and my query looks like the following:</p>
  
  <pre><code>SELECT customer.name, orders.price
  FROM customer LEFT OUTER JOIN order 
  ON customer.id = orders.customer_id 
  WHERE price IS NULL;
  </code></pre>
  
  <p>Where each customer could only have one order in the orders table at most and there are customers with no order in the orders table at all. So I am expecting to get some number of records where there is a customer in the customer table with no records in orders table which means when I do <code>LEFT OUTER JOIN</code> the price will be NULL. But this query returns 0 every time I run it. I have queries both tables separately and pretty sure there is data in both but not sure why this is returning zero where it works if I remove the <code>price IS NULL</code>. I have also tried <code>price = ''</code> and <code>price IN ('')</code> and none of them works. Has anyone here had a similar experience before? Or is there something wrong with my query that I can not see or identify?</p>