Question

I’m trying to create a custom SELECT query to find my Personal Best races from WordPress Custom Types where the times are a custom meta field.

This is the query I used to select the posts. I’ve simplified it for debugging, but eventually I want to select several term slugs and find the MIN for each using GROUP BY:

        SELECT      t.slug,
                    p.ID, 
                    p.post_date,
                    p.post_title,                    
                    m.meta_value as pb_mins
        FROM        $wpdb->posts p,
                    $wpdb->postmeta m,
                    $wpdb->term_relationships tr,
                    $wpdb->term_taxonomy tt,
                    $wpdb->terms t
        WHERE       p.ID = tr.object_id
                AND p.ID = m.post_id
                AND tr.term_taxonomy_id = tt.term_taxonomy_id
                AND tt.term_id = t.term_id
                AND p.post_type = 'runs'
                AND m.meta_key = 'ssr_duration_min'
                AND t.slug in ('10mi')

(I’m outputting the results to an array and using print_r to check it temporarily.)

This selects the two races/runs with the ’10mi’ term and displays the correct times/date/title for them.

The problem comes when I add the MIN function:

        SELECT      t.slug,
                    p.ID, 
                    p.post_date,
                    p.post_title,                    
                    MIN(m.meta_value) as pb_mins

The correct (minimum) time is selected, but the other details (date, title) are from the OTHER 10mi run/race.

I’ve tried changing the FROM clause to use LEFT JOIN and also INNER JOIN but the same thing happens: it’s fine for selecting both ’10mi’ runs but gives the wrong output when I add the MIN function.

Thanks for any help you can offer. This is my first post here so please let me know if I need to add any more details.

Answer 1

I never got round to posting my solution to this. It’s been a while now, so I can’t fully remember how I even arrived at it (most likely trial and error) but if this helps anyone, they’re welcome to it. If I think of any more details, I’ll add them as comments to this answer.

            SELECT      p1.ID,
                        m1.meta_value,
                        t1.name
            FROM        $wpdb->posts p1,
                        $wpdb->postmeta m1,
                        $wpdb->term_relationships tr1,
                        $wpdb->term_taxonomy tt1,
                        $wpdb->terms t1,
                        (   SELECT      t2.slug as pb_distance,
                                        MIN(m2.meta_value) as pb_duration
                            FROM        $wpdb->posts p2,
                                        $wpdb->postmeta m2,
                                        $wpdb->term_relationships tr2,
                                        $wpdb->term_taxonomy tt2,
                                        $wpdb->terms t2
                            WHERE       p2.ID = tr2.object_id
                                    AND p2.ID = m2.post_id
                                    AND tr2.term_taxonomy_id = tt2.term_taxonomy_id
                                    AND tt2.term_id = t2.term_id
                                    AND p2.post_type = 'runs'
                                    AND p2.post_status = 'publish'
                                    AND m2.meta_key = 'ssr_duration_min'
                                    AND t2.slug IN $slugs
                            GROUP BY    t2.slug ) pb
            WHERE       p1.ID = m1.post_id
                    AND p1.ID = tr1.object_id
                    AND tr1.term_taxonomy_id = tt1.term_taxonomy_id
                    AND tt1.term_id = t1.term_id
                    AND p1.post_type = 'runs'
                    AND p1.post_status = 'publish'
                    AND m1.meta_key = 'ssr_duration_min'
                    AND t1.slug in $slugs
                    AND m1.meta_value = pb.pb_duration
            ORDER BY    meta_value+0