在子查询中按顺序排序

Question

我有这样的查询：

SELECT i.* 
FROM items i 
WHERE i.id 
IN (
    SELECT c.item_id 
    FROM cart c 
    WHERE c.sessID=MY_SESSION_ID
   ) 

它的工作非常漂亮，但我需要按购买日期（cart.id）DESC对购物车中的商品进行分类。 我不想在PHP中排序。我如何按cart.id排序？

我试过了：

SELECT i.* 
FROM items i 
WHERE i.id 
IN (
    SELECT c.item_id 
    FROM cart c 
    WHERE c.sessID=MY_SESSION_ID
   ) 
ORDER BY c.id 

但它没有正确排序。

Answer 1

将子查询更改为Inner Join。 Sub query不允许您引用sub query之外的列。所以将其更改为Inner join

SELECT i.*
FROM   items i
       JOIN (SELECT item_id,
                    id
             FROM   cart) C
         ON i.id = c.item_id
            AND c.sessID = MY_SESSION_ID
ORDER  BY c.id Desc

或使用此。

SELECT i.*
FROM   items i
       JOIN cart C
         ON i.id = c.item_id
            AND c.sessID = MY_SESSION_ID
ORDER  BY c.id Desc

Answer 2

试试这个：

SELECT i.* 
FROM items i 
INNER JOIN cart c ON i.id = c.item_id 
WHERE c.sessID = MY_SESSION_ID 
GROUP BY i.id 
ORDER BY MAX(c.id) DESC;

或

SELECT i.* 
FROM items i 
INNER JOIN (SELECT item_id, MAX(id) AS cid 
            FROM cart 
            WHERE sessID = MY_SESSION_ID 
            GROUP BY item_id
          ) AS c ON i.id = c.item_id 
ORDER BY c.cid DESC;

Answer 3

尝试此查询：

SELECT i.* FROM items i LEFT OUTER JOIN cart c 
ON i.id = c.item_id WHERE c.sessID=MY_SESSION_ID AND 
c.item_id is not null ORDER BY c.id