title: SQL query to JOIN two tables with no relationship
body: <p>I am having trouble getting the records on the Monthly average Cost per Item with this table values.
  <a href="https://i.stack.imgur.com/MzGgT.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MzGgT.jpg" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/Xx3fR.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Xx3fR.jpg" alt="enter image description here"></a></p>
  
  <p>I need a result like this:</p>
  
  <p><a href="https://i.stack.imgur.com/luba2.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/luba2.jpg" alt="enter image description here"></a></p>
  
  <p>What I want to get is all the month from January to December even if there is no transaction on that month of that item.</p>
  
  <p>Is this possible ?</p>