How does Drupal 7's SQL call for 'node' and retrieve an image? I have the following query shown in one of my views:

SELECT node.nid AS nid, node.title AS node_title, node.created AS node_created, 
node.sticky AS node_sticky, 
'node' AS field_data_field_featured_image_node_entity_type, 
'node' AS field_data_body_node_entity_type, 
'node' AS field_data_field_premium_content_node_entity_type, 
'node' AS field_data_field_article_type_node_entity_type, 
'node' AS field_data_field_video_upload_node_entity_type
    FROM 
    {node} node
    INNER JOIN {field_data_field_sports_type} field_data_field_sports_type ON node.nid = field_data_field_sports_type.entity_id AND (field_data_field_sports_type.entity_type = 'node' AND field_data_field_sports_type.deleted = '0')
    WHERE (( (node.status = '1') AND (node.type IN  ('article')) AND (field_data_field_sports_type.field_sports_type_tid = '1884') ))
    ORDER BY node_sticky DESC, node_created DESC
    LIMIT 8 OFFSET 1


What does the 'node' in this query return, for instance when I'm calling:

...'node' AS field_data_field_featured_image_node_entity_type,


It seems to me that this should just return the string "node" but in the preview it's actually showing the image. When I do the SQL query in the console it's just returning the string 'node'. I'm confused because I don't see any JOIN statements on things like the field_featured_image table in this query, which I would have expected if the query actually was pulling the image. 

How is the image getting shown via this query?
It's utilizing a loaded entity to fill in these placeholder columns. Per the views_handler_field_field::query() docs:


  By default, the only columns added to the query are entity_id and
  entity_type. This is because other needed data is fetched by
  entity_load(). Other columns are added only if they are used in
  groupings, or if 'add fields to query' is specifically set to TRUE in
  the field definition.


In the post-execute phase, during views_handler_field_field::post_execute(),  you can see where the field values are dropped in from the entity values.