Any Mysql guru to help me please to retrieve a sum of meta_value

It’s not the subject but I have builded another option with SELECT meta_key, sum(meta_value) AS my_total FROM $wpdb->postmeta WHERE meta_key=%s GROUP BY meta_key

but to group the sum(meta_value) from this meta_key (placed in all posts) foreach categories I have difficulties.

If a user comes here, after studies and some tries I have this. But currently this solution don’t exclude the “links” taxonomy.

$meta_key = 'your_meta';

$request = $wpdb->get_results($wpdb->prepare(
"
SELECT sum(meta_value) AS total, name 

FROM $wpdb->postmeta AS pm, $wpdb->posts AS p, $wpdb->term_relationships AS tr, $wpdb->terms AS t 

WHERE pm.post_id=p.ID
AND p.post_status='publish'
AND pm.post_id=tr.object_id
AND tr.term_taxonomy_id=t.term_id
AND meta_key=%s
GROUP BY t.name
",
$meta_key));

INNER JOIN, LEFT JOIN, JOIN, RIGHT JOIN,… is a “new” more clear/flexible clause recommended in replacement of WHERE (nothing else).

Only the total sum of a meta_key -> value pair placed in multiple posts with taxonomy relation “category” only.

$meta_key = 'your_meta';

$request = $wpdb->get_results($wpdb->prepare(
"
SELECT sum(meta_value) AS total, name 

FROM $wpdb->postmeta AS pm, $wpdb->posts AS p, $wpdb->term_relationships AS tr, $wpdb->term_taxonomy AS tt, $wpdb->terms AS t 

WHERE pm.post_id=p.ID AND p.post_status='publish'
AND pm.post_id=tr.object_id
AND tr.term_taxonomy_id=tt.term_taxonomy_id
AND tt.taxonomy='category'
AND tr.term_taxonomy_id=t.term_id
AND meta_key=%s
GROUP BY t.name
ORDER BY total DESC
",
$meta_key));