A few Wordpress SQL queries

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