query(" DELETE pm FROM {$wpdb->postmeta} pm JOIN ( SELECT post_id, meta_id FROM ( SELECT post_id, meta_id, ROW_NUMBER() OVER (PARTITION BY post_id ORDER BY meta_id DESC) AS row_num FROM {$wpdb->postmeta} WHERE meta_key = 'inline_featured_image' ) as duplicates WHERE row_num > 1 ) to_delete ON pm.meta_id = to_delete.meta_id "); // Delete all inline_featured_image meta entries that aren't explicitly set to 1 $wpdb->query(" DELETE FROM {$wpdb->postmeta} WHERE meta_key = 'inline_featured_image' AND (meta_value = '' OR meta_value = '0' OR meta_value IS NULL) "); }