sql - 在不同的表中返回最近的日期

Question

我有两张表，一张叫做 Events，一张叫做 Documents。每个表都有两个日期列，开始和结束(因此事件开始、事件结束、文档开始、文档结束)。两个表都通过名为 Customer_ID 的字段链接。我有兴趣根据客户 ID 将最接近的相关事件开始(及其 ID)日期返回到 Doc 开始日期，因此例如表中的数据可能如下所示:

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

我希望最终结果显示如下:

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

我已经尝试通过谷歌搜索解决方案，并尝试了一个或两个建议，但我能找到的所有示例似乎都不是用于比较跨表的日期，甚至是用于 Oracle 的。此外，我对 SQL 的了解相当有限，但我学到的大部分知识都来自这里，所以非常感谢我已经收到的帮助。

编辑:另一个条件是我只想返回相关的事件/文档类型。所以我只想带回 DOC_ID，其中 DOC_TYPE 是“查询”或“信息”，Event_Type 也是如此。

编辑:谢谢文森特，我按照建议将 where 放入(我想我已经在所有地方都试过了，但那里!)现在我得到了所需的结果。

如果有人感兴趣，我会发布工作解决方案以供将来引用:

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