title: orientdb sql query to select edge and vertex fields property.
body: <p>I do have following database structure. </p>
  
  <p>users -> comment -> products</p>
  
  <p>a. users and products are the vertexes that contain some info etc: user_name, product_name and ....
  b. comment is the edge that contains comment and created/modified date. </p>
  
  <p>what is the sql query may look like in order to show the following result. </p>
  
  <p>Note: i have to show all of the products that may have or no have comment. </p>
  
  <ol>
  <li>product_name, user_name, comment, comment_created_date, comment_modified_date</li>
  <li>product_name, user_name, '', '', ''</li>
  <li>product_name, user_name, comment, comment_created_date, comment_modified_date</li>
  </ol>