title: Select rows that don't exist in other table
body: <p><a href="https://i.stack.imgur.com/RH4WQ.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RH4WQ.jpg" alt="SQL Tables"></a>
  Let's suppose I have 4 tables as above. BOM means Bill of Materials. As you can see, Production Order 1 is missing 1 item from it's BOM (ITEM3) and Production Order 2 is missing other item (ITEM1). Given a BOM code, how do I get every production order that is missing an item and which item is that? The result would be something like:</p>
  
  <pre><code>ID | Item
  ---|------
  1  | ITEM3
  2  | ITEM1
  </code></pre>