Question

我需要一个SQL查询（MySQL）的“小”帮助。

我有以下表格：

COURIERS表：

    +------------+
    | COURIER_ID |
    +------------+

DELIVERIES表：

    +-------------+------------+------------+
    | DELIVERY_ID | COURIER_ID | START_DATE |
    +-------------+------------+------------+

ORDERS表：

    +----------+-------------+-------------+
    | ORDER_ID | DELIVERY_ID | FINISH_DATE |
    +----------+-------------+-------------+

COORDINATES表：

    +-------------+-----+-----+------+
    | DELIVERY_ID | LAT | LNG | DATE |
    +-------------+-----+-----+------+

在真实数据库中，每个表中有更多列，但对于此示例，上面的列就足够了。

我需要什么？

返回所有信使[COURIER_ID]的SQL查询交付[DELIVERY_ID]（基于最后START_DATE），交货的最后一个坐标[LAT和LNG]（基于最后DATE）和剩余订单数（最后交货的订单总数没有FINISH_DATE）。< / p>
快递员没有送货，在这种情况下，我想要DELIVERY_ID = 结果中为NULL，LAT = NULL且LNG = NULL。
传递可以没有坐标，在这种情况下我希望LAT = NULL 结果中LNG = NULL。

我能做什么？

SELECT c.`COURIER_ID`,
       d.`DELIVERY_ID`,
       r.`LAT`,
       r.`LNG`,
  (SELECT COUNT(DISTINCT `ORDER_ID`)
   FROM `ORDERS`
   WHERE `DELIVERY_ID` = d.`DELIVERY_ID`
     AND `FINISH_DATE` IS NULL) AS REMAINING_ORDERS

FROM `COURIERS` AS c
LEFT JOIN `DELIVERIES` AS d USING (`COURIER_ID`)
LEFT JOIN `COORDINATES` AS r ON r.`DELIVERY_ID` = d.`DELIVERY_ID`

WHERE (CASE WHEN
         (SELECT MAX(`START_DATE`)
          FROM `DELIVERIES`
          WHERE `COURIER_ID` = c.`COURIER_ID`) IS NULL THEN d.`START_DATE` IS NULL ELSE d.`START_DATE` =
         (SELECT MAX(`START_DATE`)
          FROM `DELIVERIES`
          WHERE `COURIER_ID` = c.`COURIER_ID`) END)
  AND (CASE WHEN
         (SELECT MAX(`DATE`)
          FROM `COORDINATES`
          WHERE `DELIVERY_ID` = d.`DELIVERY_ID`) IS NULL THEN r.`DATE` IS NULL ELSE r.`DATE` =
         (SELECT MAX(`DATE`)
          FROM `COORDINATES`
          WHERE `DELIVERY_ID` = d.`DELIVERY_ID`) END)
GROUP BY c.`COURIER_ID`
ORDER BY d.`START_DATE` DESC

问题是，当我有超过5k COORDINATES并且有时不会返回所有信使时，此查询非常慢（从5秒到20秒）。

非常感谢您的任何解决方案。

Answer 1

试试这个：

SELECT C.COURIER_ID, D.DELIVERY_ID, D.START_DATE, D.FINISH_DATE, 
       B.LAT, B.LNG, B.DATE, C.NoOfOrders
FROM COURIERS C 
LEFT JOIN ( SELECT * 
            FROM (SELECT * 
                  FROM DELIVERIES D 
                  ORDER BY D.COURIER_ID, D.START_DATE DESC
                ) A 
            GROUP BY COURIER_ID
          ) AS A ON C.COURIER_ID = A.COURIER_ID 
LEFT JOIN ( SELECT * 
            FROM (SELECT * 
                  FROM COORDINATES CO 
                  ORDER BY CO.DELIVERY_ID, CO.DATE DESC
                ) B
            GROUP BY CO.DELIVERY_ID
          ) AS B ON A.DELIVERY_ID = B.DELIVERY_ID 
LEFT JOIN ( SELECT O.DELIVERY_ID, COUNT(1) NoOfOrders
            FROM ORDERS O WHERE FINISH_DATE IS NULL
            GROUP BY O.DELIVERY_ID
          ) AS C ON A.DELIVERY_ID = C.DELIVERY_ID;

Answer 2

我无法测试此查询，因为我现在没有设置mysql数据库，更不用说这个架构和示例数据了。但我认为这对你有用：

select
  c.courier_id
  , d.delivery_id
  , co.lat
  , co.lng
  , oc.cnt as remaining_orders
from
  couriers c
  left join (
    select
      d.delivery_id
      , d.courier_id
    from
      deliveries d
      inner join (
        select
          d.delivery_id
          , max(d.start_date) as start_date
        from
          deliveries d
        group by
          d.delivery_id
      ) dmax on dmax.delivery_id = d.delivery_id and dmax.start_date = d.start_date
  ) d on d.courier_id = c.courier_id
  left join (
    select
      c.delivery_id
      , c.lat
      , c.lng
    from
      coordinates c
      inner join (
        select
          c.delivery_id
          , max(c.date) as date
        from
          coordinates c
        group by
          c.delivery_id
      ) cmax on cmax.delivery_id = c.delivery_id and cmax.date = c.date
  ) co on co.delivery_id = d.delivery_id
  left join (
    select
      o.delivery_id
      , count(o.order_id) as cnt
    from
      orders o
    where
      o.finish_date is null
    group by
      o.delivery_id
  ) oc on oc.delivery_id = d.delivery_id

加入几个表的SQL查询（MySQL）

2 个答案: