加盟條件：通過日期時間

讓步

Shipment_id，標題，Creation_datetime

1, A, 2017-09-13

只選擇最後一個記錄，每一讓步有一個以上的SCAN

SCANS

Shipment_ID, Event_code, TSS_creation_date  
1, 200, 2017-09-10  
1, 400, 2017-09-11  
1, 600, 2017-09-12  
1, 800, 2017-09-15  
1, 900, 2017-09-16

在我最後的結果我想

結果（特許）

Shipment_ID,Title, Creation_datetime, LAST_SCAN_AT_CREATION_DATE 

1, A, 2017-09-13, 600

在那裏我得到了event_code=600因爲這是最後一排有creation_date <= concession_creation_date

我有這個嘗試查詢，但實際上效率低下，而且速度太慢，導致無法獲得結果。你知道如何使用Join嗎？

WITH 

ShipmentAndScans AS (
    SELECT 
     conc.shipment_id, 
     (
      SELECT 
       scan.event_code 
      FROM SCANS_TABLE scan 
      WHERE 
        scan.shipment_id = conc.shipment_id 
       AND scan.TSS_CREATION_DATE <= conc.CREATION_DATETIME 
       AND ROWNUM <=1 

     ) AS LAST_SCAN_AT_CONCESSION_TIME   
    FROM CONCESSIONS conc   
) 
SELECT * 
FROM ShipmentAndScans 
WHERE LAST_SCAN_AT_CONCESSION_TIME IS NOT NULL

來源

2017-09-13 Leo

我相信你想要的以下內容：

select sc.* 
from (select c.*, s.event_code, s.TSS_CREATION_DATE, 
      row_number() over (partition by c.shipment_id order by s.tss_creation_date desc) as seqnum 
     from concessions c join 
      scan s 
      on s.shipment_id = c.shipment_id and 
       s.TSS_CREATION_DATE <= c.CREATION_DATETIME 
    ) cs 
where seqnum = 1;

在您的版本中，CTE基本上是做一個LEFT JOIN（通過一個相關的子查詢）。然而，外部查詢將該邏輯重新轉換爲JOIN。

來源

2017-09-13 10:27:50

似乎有效。你知道我怎樣才能得到最後的紀錄（最近的）？ – Leo

千萬的加入，使用ROW_NUMBER（）

with CTE as 
(
select c1.*, s2.*, 
     row_number() over(partition by c1.shipment_id order by TSS_creation_date desc) as rn 
from Concessions 
inner join SCANS s2 
on s2.shipment_id = c1.shipment_id 
) 
select * 
from CTE 
where rn = 1

來源

2017-09-13 10:22:33 JohnHC

加盟條件：通過日期時間

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