Question

我有一张这样的桌子：

OrderID   OrderStatus     DateCreated
--------------------------------------------
13     3             2018-10-25 09:33:14.937
13     4             2018-10-25 09:33:19.010
13     7             2018-10-25 18:03:37.137
14     3             2018-10-25 09:43:45.363
14     4             2018-10-25 09:43:50.690
14     7             2018-10-25 09:54:55.150
15     2             2018-10-25 14:04:06.380
16     3             2018-10-25 14:31:53.060
16     4             2018-10-25 14:32:00.040
16     7             2018-10-25 14:39:10.160
17     3             2018-10-25 15:52:20.750
17     4             2018-10-25 15:52:35.937
17     7             2018-10-25 18:03:47.130
18     3             2018-10-25 15:58:47.923
18     4             2018-10-25 15:59:00.420
18     7             2018-10-25 18:03:47.160

有8种状态。我想要一个查询，该查询返回每个状态的订单ID和dateCreated。如果状态被跳过，我希望有一个空值。

例如，

OrderId    status1    status2  status3  ....   status8
-------------------------------------------------------
 12          time        null     time   ....    time

我尝试使用多个联接，但是事实证明，大多数情况下状态被跳过是一个问题。

select 
    o1.OrderId,
    o1.DateCreated as 'AwaitingExternalPayment', 
    o2.DateCreated as 'PaymentSettledButNotYetSuppliedToStore', 
    o3.DateCreated as 'ReceivedByStore', 
    o4.DateCreated as 'InOven',
    o5.DateCreated as 'ReadyForDispatch',
    o6.DateCreated as 'OutForDelivery',
    o7.DateCreated as 'Completed',
    o8.DateCreated as 'Canceled'
from 
    OrderStatusHistory as o1
left join 
    OrderStatusHistory as o2 on o1.OrderId = o2.OrderId
                             and case
                                    when o2.OrderStatusEnum = 2 then 1
                                    else 0
                                 end = 1
left join 
    OrderStatusHistory as o3 on o2.OrderId = o3.OrderId
                             and case
                                    when o3.OrderStatusEnum = 3 then 1
                                    else 0
                                 end = 1
-- repeat this "left join" for every status

Answer 1

您可以使用条件聚合：

select osh.OrderID,
       min(case when OrderStatus = 1 then DateCreated end) as status_1,
       min(case when OrderStatus = 2 then DateCreated end) as status_2,
       min(case when OrderStatus = 3 then DateCreated end) as status_3,
       min(case when OrderStatus = 4 then DateCreated end) as status_4,
       min(case when OrderStatus = 5 then DateCreated end) as status_5,
       min(case when OrderStatus = 6 then DateCreated end) as status_6,
       min(case when OrderStatus = 7 then DateCreated end) as status_7,
       min(case when OrderStatus = 8 then DateCreated end) as status_8
from OrderStatusHistory osh
group by osh.OrderID;

将值排序到不同的列中

1 个答案: