title: SQL - Products with No Sales
body: <p>I'm trying to list all the Products that have had no sales. I'm really close but I'm trying to use the NOT EXISTS statement to display all the ProductID's that are in the Product table, but not in the Orderline table; and hence have no sales. My code is as follows; </p>
  
  <pre><code>SELECT product.productid
  FROM product
  JOIN orderline ON product.productid = orderline.productid
  WHERE NOT EXISTS (
  
  SELECT orderline.productid
  FROM orderline
  )
  ORDER BY productid
  </code></pre>