提高查询性能

Question

I'm trying to optimize this query:

SELECT post_id 
FROM wp_postmeta
WHERE meta_key = 'passenger_group_id'
AND meta_value in (SELECT post_id 
                   FROM wp_postmeta 
                   WHERE meta_key = 'group_event' AND meta_value = '14608')
AND post_id IN (SELECT post_id 
                FROM wp_postmeta 
                WHERE meta_value='Cancelled')
AND post_id NOT IN (SELECT ID 
                    FROM wp_posts 
                    WHERE post_status='trash') 

Any help would be greatly appreciated.

Answer 1

you can use EXISTS clause alone and add NOT IN condition can be made NOT EXISTS

select wp1.post_id 
from wp_postmeta wp1
WHERE meta_key = 'passenger_group_id'
and exists  ( select 1 FROM
              wp_postmeta wp2
              where ( (wp2.meta_key = 'group_event' AND wp2.meta_value = '14608' ) or wp2.meta_value ='Cancelled' )
              and wp2.post_id = wp1.meta_value 

            )
and not exists ( select 1 from
                 wp_posts p
                 on p.id = wp1.post_id
                 and p.post_status = 'trash')
                )