Need help with MySQL, joining two queries.

Question

Hi, I'm running WordPress and I'd like to write a custom query that would show a monthly archive of posts based on one specific category. I used the debug mode to find out how to get a monthly archive based on all posts, select a specific category. Here are the queries:

Get montlhy archive:

SELECT YEAR(post_date) AS `year`, MONTH (post_date) AS `month`, 
  count(ID) as posts FROM wp_posts  
  WHERE post_type = 'post' AND post_status = 'publish' 
  GROUP BY YEAR(post_date), MONTH(post_date) ORDER BY post_date DESC

Select category:

SELECT t.*, tt.* FROM wp_terms AS t INNER JOIN wp_term_taxonomy
  AS tt ON t.term_id = tt.term_id WHERE tt.taxonomy 
  IN ('category')  AND t.slug = 'blog' ORDER BY t.name ASC

I can't figure out how to join these two ;) Any help appreciated!

Thanks.

Update:

There's also another table involved called term_relationships, so that makes 4 tables in total. Here's an image of WordPress' database structure: http://codex.wordpress.org/images/8/83/WP_27_dbsERD.png

Anyways, here's where I'm at:

SELECT t.*, tt.*, YEAR(post_date) AS `year`, MONTH(post_date) AS `month`, 
    count(ID) as posts FROM wp_posts, wp_term_relationships AS tr, 
    wp_terms AS t INNER JOIN wp_term_taxonomy AS tt ON t.term_id = tt.term_id 
    WHERE tt.taxonomy IN ('category') AND t.slug = 'blog' 
    AND post_type = 'post' AND post_status = 'publish' 
    AND ID = tr.object_id AND tr.term_taxonomy_id = t.term_id 
    GROUP BY YEAR(post_date), MONTH(post_date) ORDER BY post_date DESC

I know it's not the best way around, and that's why I need your help ;)

Thanks.

Answer 1

How about something like this as the basis for the joins and where clause additions that you need:

    SELECT 
        YEAR(post_date) AS `year`, 
        MONTH (post_date) AS `month`, 
        count(ID) as posts  
    FROM wp_posts 
    INNER JOIN wp_term_relationships wtr ON wp_posts.id = wtr.object_id
    INNER JOIN wp_term_taxonomy wtt ON wtr.term_taxonomy_id = wtt.term_taxonomy_id
    INNER JOIN wp_terms wt ON wtt.term_id = wt.term_id
    WHERE post_type = 'post' AND post_status = 'publish' 
    AND wtt.taxonomy = 'category'
    AND wt.name = 'enter category name here'
    GROUP BY YEAR(post_date), MONTH(post_date) ORDER BY post_date DESC