相当于Oracle超前和滞后功能的Teradata [英] Teradata equivalent for lead and lag function of oracle

问题描述

我一直在努力，看到与Oracle超前和滞后功能等效的功能.

I have been working ot see the equivalent function for Oracle lead and lag function.

甲骨文线索看起来像

LEAD(col1.date,1,ADD_MONTHS(col1.DATE,12)) 
OVER(Partition By tab.a,tab.b,tab.c Order By tab.a)-1 END_DATE

LAG(col1.DATE + 7,1,col1.DATE-1) 
OVER(partition by tab.a,tab.b Order By tab.b) LAG_DATE

任何更好的主意

推荐答案

我相信您可以将以下SQL作为基础并对其进行修改以满足您的需求:

I believe you can take the following SQL as a basis and modify it to meet your needs:

SELECT CALENDAR_DATE
     , MAX(CALENDAR_DATE)
       OVER(PARTITION BY 1 ORDER BY CALENDAR_DATE
            ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING) AS Lag_ --Yesterday
     , MIN(CALENDAR_DATE)
            OVER(PARTITION BY 1 ORDER BY CALENDAR_DATE
            ROWS BETWEEN 1 FOLLOWING AND 1 FOLLOWING) AS Lead_ --Tomorrow
FROM SysCalendar.CALENDAR
WHERE year_of_calendar = 2011
  AND month_of_year = 11

如果之前或之后没有记录，则返回NULL，并且可以根据需要使用COALESCE对其进行寻址.

NULL is returned when there is no record before or after and can be addressed with a COALESCE as necessary.

编辑.在Teradata 16.00中，引入了LAG/LEAD功能.

EDIT In Teradata 16.00 LAG/LEAD functions were introduced.

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