Mysql usa DESC nell'istruzione case

Question

nel comando sql sottostante voglio usare DESC dopo la riga WHEN 1 THEN i.id. voglio se sortable campo è 1 per poi dai deve essere hanno come questo comando,

ORDER BY i.id DESC 

Mysql:

SELECT 
    SQL_CALC_FOUND_ROWS i.* , 
    c.title AS category_name, 
    u.name, 
    u.family, 
    i.thumb_image, 
    CONCAT(u.name, ' ', u.family) AS author, 
    tumbnail_image_width, 
    tumbnail_image_height 
    FROM contents i 
    JOIN categories c ON c.id = i.category 
    JOIN users u ON u.id = i.posted_by 
    JOIN settings s ON s.portal = i.portal 
    WHERE 
     i.portal = '{$portal_id}' 
     AND CASE WHEN post_type = 4 
       THEN date(NOW()) BETWEEN i.from_dateTime AND i.to_dateTime 
     ELSE post_type = 1 
     END 
    AND i.t_status = 1 
    ORDER BY 
    CASE (SELECT sortable FROM settings) 
     WHEN 1 THEN i.id 
     WHEN 2 THEN i.date_time 
     WHEN 3 THEN i.order_display 
    END       
    LIMIT {$portalSettings['display_post_count']};"; 

Answer 1

Possibilmente riportare il campo di ordinamento nella SELECT e poi ordina per quel campo denominato: -

SELECT 
    SQL_CALC_FOUND_ROWS i.* , 
    c.title AS category_name, 
    u.name, 
    u.family, 
    i.thumb_image, 
    CONCAT(u.name, ' ', u.family) AS author, 
    tumbnail_image_width, 
    tumbnail_image_height, 
    CASE (s.sortable) 
     WHEN 1 THEN 100000000 - i.id 
     WHEN 2 THEN i.date_time 
     WHEN 3 THEN i.order_display 
    END AS SortField 
    FROM contents i 
    JOIN categories c ON c.id = i.category 
    JOIN users u ON u.id = i.posted_by 
    JOIN settings s ON s.portal = i.portal 
    WHERE 
     i.portal = '{$portal_id}' 
     AND CASE WHEN post_type = 4 
       THEN date(NOW()) BETWEEN i.from_dateTime AND i.to_dateTime 
     ELSE post_type = 1 
     END 
    AND i.t_status = 1 
    ORDER BY SortField     
    LIMIT {$portalSettings['display_post_count']};"; 

Nota che potrebbe essere necessario eseguire il cast dei campi su un tipo di dati per eseguire questa operazione.