Question

我对以下mySQL查询有问题，当引入最大日期时，它失败，如下所示。我收到以下错误

错误代码：1054。“ where”中的未知列“ order_items.ORDER_ITEM_ID” 条款”

SET @UserID = 160;
SET @OrderDateTime = '2018-11-13 09:23:45';

SELECT 
order_items.ORDER_ID,
listing_region.LIST_REGION_REGION_ID,
listings.LISTING_ID,
order_items.ORDER_REQUIRED_DATE_TIME,
listings.LISTING_NICK_NAME,
order_items.ORDER_QUANTITY,
order_price.ORDER_PRICE_ID,
order_items.ORDER_PORTION_SIZE,
t.LATEST_DATE,
t.ORDER_STATUS


FROM order_status_change, order_items 

INNER JOIN listings ON listings.LISTING_ID = order_items.ORDER_LISTING_ID
INNER JOIN listing_region ON listing_region.LIST_REGION_LISTING_ID = listings.LISTING_ID
INNER JOIN order_price ON order_price.ORDERP_ITEM_ID = order_items.ORDER_ITEM_ID
INNER JOIN 
  (
     SELECT MAX(order_status_change.ORDER_STATUS_CHANGE_DATETIME) AS LATEST_DATE, order_status_change.ORDER_ITEM_ID, order_status_change.ORDER_STATUS
     FROM order_status_change
     WHERE order_status_change.ORDER_ITEM_ID = order_items.ORDER_ITEM_ID
  ) AS t ON order_status_change.ORDER_ITEM_ID = t.ORDER_ITEM_ID AND order_status_change.ORDER_STATUS_CHANGE_DATETIME = t.LATEST_DATE 

WHERE ((order_items.ORDER_USER_ID = @UserID) AND DATE(order_items.ORDER_REQUIRED_DATE_TIME) = DATE(@OrderDateTime))

有帮助吗？

Answer 1

这是一个简化的版本来说明问题。

DROP TABLE IF exists t,t1;

create table t (id int);
create table t1(id int,dt date);

insert into t values (1),(2);
insert into t1 values (1,'2018-01-01'),(1,'2018-02-01'),(2,'2018-01-01');

select t.*,t2.maxdt
from t
join (select max(dt) maxdt,t1.id from t1 where t1.id = t.id) t2
    on t2.id = t.id;

ERROR 1054 (42S22): Unknown column 't.id' in 'where clause'

您可以在子查询中分组，然后on子句将起作用

select t.*,t2.maxdt
from t
join (select max(dt) maxdt,t1.id from t1 group by t1.id) t2
    on t2.id = t.id;

+------+------------+
| id   | maxdt      |
+------+------------+
|    1 | 2018-02-01 |
|    2 | 2018-01-01 |
+------+------------+
2 rows in set (0.00 sec)

如果您想要更接近问题的答案，请向sqlfiddle中添加示例数据和期望的输出作为问题的文本。

Answer 2

我假设您可以加入order_status_change on order_items.ID = order_status_change.ORDER_ITEM_ID

如果这是有效的，那么我认为这将达到您追求的目标：

SET @UserID = 160;
SET @OrderDateTime = '2018-11-13 09:23:45';


SELECT
    order_items.ORDER_ID
  , listing_region.LIST_REGION_REGION_ID
  , listings.LISTING_ID
  , order_items.ORDER_REQUIRED_DATE_TIME
  , listings.LISTING_NICK_NAME
  , order_items.ORDER_QUANTITY
  , order_price.ORDER_PRICE_ID
  , order_items.ORDER_PORTION_SIZE
  , t.LATEST_DATE
  , order_status_change.ORDER_STATUS
FROM order_items
INNER JOIN listings ON listings.LISTING_ID = order_items.ORDER_LISTING_ID
INNER JOIN listing_region ON listing_region.LIST_REGION_LISTING_ID = listings.LISTING_ID
INNER JOIN order_price ON order_price.ORDERP_ITEM_ID = order_items.ORDER_ITEM_ID

INNER JOIN order_status_change ON order_items.ID = order_status_change.ORDER_ITEM_ID
INNER JOIN (
        SELECT
            MAX( mc.ORDER_STATUS_CHANGE_DATETIME ) AS LATEST_DATE
          , mc.ORDER_ITEM_ID
        FROM order_status_change AS mc
        GROUP BY
            mc.ORDER_ITEM_ID
    ) AS t
             ON order_status_change.ORDER_ITEM_ID = t.ORDER_ITEM_ID
            AND order_status_change.ORDER_STATUS_CHANGE_DATETIME = t.LATEST_DATE 

WHERE order_items.ORDER_USER_ID = @UserID
AND DATE( order_items.ORDER_REQUIRED_DATE_TIME ) = DATE( @OrderDateTime )

您将来需要避免这种情况：

FROM order_status_change  , order_items

两个表名之间的逗号 IS 是一个联接，但这是来自较旧的语法，并且优先级比查询的其他联接低。同样，默认情况下，这种基于逗号的联接相当于cross join的乘积，该乘数乘以行数。简而言之，请不要在表名之间使用逗号。

另一个问题是，您缺少一个group by子句，并且我相信您只是想从此聚合中获取“最新”日期，一旦确定该日期，就可以链接回该表以获取与之相关的状态那个日期。（即，您无法在子查询中按状态分组，否则您将获得最新的dateS（每个状态一个）。

为什么我不能以最大日期加入此查询？

2 个答案: