SQL to get all posts in WordPress for a given category id (this is assuming that you have the default “wp_” prefix on the table name and you know the “term_id” of your category):
SELECT * FROM wp_posts INNER JOIN wp_term_relationships ON (wp_posts.ID = wp_term_relationships.object_id) INNER JOIN wp_term_taxonomy ON (wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id) WHERE (wp_term_taxonomy.term_id = 23 AND wp_term_taxonomy.taxonomy = 'category' AND wp_posts.post_type = 'post' AND wp_posts.post_status = 'publish');
Code to select the current version of a post given that you know the ID of it from a previous query:
SELECT * FROM wp_posts WHERE ID=300 AND post_status = 'publish'
SQL to view all unique categories:
SELECT distinct t.term_id, name, count FROM wp_term_taxonomy tt INNER JOIN wp_terms t on tt.term_id = t.term_id WHERE taxonomy = 'category'
SQL to select latest articles:
SELECT id, post_title FROM wp_posts WHERE post_status = 'publish' AND post_type = 'post' ORDER BY post_date desc LIMIT 5