在不同的表格中返回到最近的日期

Question

我有两个表，一个叫做Events，一个叫做Documents。每个表格有两个日期列，开始和结束（所以事件开始，事件结束，文档开始，文档结束）。两个表都通过名为Customer_ID的字段进行链接。我感兴趣的是返回最接近的相关事件开始（和它的ID），根据客户ID日期到文档开始日期，因此，例如表中的数据可能看起来像：

Customer_ID DOC_ID  DOC_Start DOC_END 
A   12   22/01/2011 23/01/2011 
A   13   01/12/2011 05/12/2011 
C   22   13/03/2011 20/03/2011 


Customer_ID Event_ID Event_Start Event_END 
A   J1   01/01/2011 23/01/2011 
A   J2   04/12/2011 05/12/2011 
C   J44   15/03/2011 20/03/2011 

我会想最终的结果显示如下：

Customer_ID DOC_ID DOC_Start DOC_END  Event_ID 
A   12  22/01/2011 23/01/2011 J1 
A   13  01/12/2011 05/12/2011 J2 
C   22  13/03/2011 20/03/2011 J44 

我试着用搜索引擎的解决方案，并尝试一项两个建议，但没有一个例子，我可以找到似乎是跨表，甚至是比较日期甲骨文。另外，在SQL方面，我的知识相当有限，但大部分我已经从这里获得，所以非常感谢我已经收到的帮助。

编辑：另一个条件是我想只返回相关的事件/文档类型。因此，我只想将DOC_TYPE为“Inquiry”或“Info”的DOC_ID取回，对于Event_Type也是如此。

编辑：谢谢文森特，我把建议的地方放在那里（想想我到处都试过了，但在那里！），我现在正在得到所需的结果。

我会后以供将来参考的工作溶液中，如果有人有兴趣：

SELECT 
* 

FROM (SELECT 
O_ASSESSMENTS.ASM_SUBJECT_ID as "ID", 
O_ASSESSMENTS.ASM_ID as "Assessment ID", 
O_ASSESSMENTS.ASM_START_DATE as "Assessment Start", 
O_ASSESSMENTS.ASM_END_DATE as "Assessment End", 
O_SERVICE_EVENTS.SEV_ID as "Event ID", 
O_SERVICE_EVENTS.SEV_ACTUAL_DATE as "Event Start", 
O_SERVICE_EVENTS.SEV_OUTCOME_DATE as "Event End", 
ROUND(O_ASSESSMENTS.ASM_START_DATE -O_SERVICE_EVENTS.SEV_ACTUAL_DATE,0) as "Likely", 
    row_number() over(PARTITION BY O_ASSESSMENTS.ASM_ID          
ORDER BY abs(O_ASSESSMENTS.ASM_START_DATE - O_SERVICE_EVENTS.SEV_ACTUAL_DATE)) rn    
FROM 
O_ASSESSMENTS 
JOIN O_SERVICE_EVENTS ON O_ASSESSMENTS.ASM_SUBJECT_ID = O_SERVICE_EVENTS.SEV_SUBJECT_ID 
Where O_SERVICE_EVENTS.SEV_CODE IN ('t','t1') AND O_ASSESSMENTS.ASM_QSA_ID IN ('test','test1') ) WHERE rn = 1 

Answer 1

您可以使用analytics：

SELECT * 
    FROM (SELECT d.customer_id, d.doc_id, d.doc_start, d.doc_end, e.event_id, 
       row_number() over(PARTITION BY d.doc_id 
            ORDER BY abs(d.doc_start - e.event_start)) rn 
      FROM doc d 
      JOIN event e ON d.customer_id = e.customer_id 
     /*WHERE CLAUSE*/) 
WHERE rn = 1 

Answer 2

加入Events和Documents，只选择最接近DOC_Start加入行和Event_Start

select D1.Customer_ID, D1.DOC_ID, D1.DOC_Start, D1.DOC_END, E1.Event_ID 
from Events E1, Documents D1 
where E1.Customer_ID = D1.Customer_ID 
and (D1.Customer_ID, D1.DOC_ID, E1.Event_ID) in 
(
    select D2.Customer_ID, D2.DOC_ID, E2.Event_ID 
    from Events E2, Documents D2 
    where E2.Customer_ID = D2.Customer_ID 
    group by D2.Customer_ID, D2.DOC_ID, E2.Event_ID 
    having abs(D2.DOC_Start - E2.Event_Start) = min(abs(D2.DOC_Start - E2.Event_Start)) 
);