You want to query a Wordpress database and get out ther pertinent information related to the current version of a post. The following query works and has been tested with both MySql and a SQLite implementation with Wordpress 4.0. It is look for published posts and pulling back the main information on the post plus who authored it.
from wp_posts wp
left outer join wp_users wu on wu.ID = wp.post_author
where post_status = 'publish' and post_type = 'post'