Teradata 相当于 Oracle 的超前和滞后功能

Question

我一直在努力寻找 Oracle 超前和滞后函数的等效函数。

甲骨文领导看起来像

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

Answer 1

我相信你可以以下面的SQL为基础，修改它来满足你的需求：

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

前后没有记录时返回NULL，必要时可以用COALESCE解决。

编辑 Teradata 16.00 中引入了 LAG/LEAD 功能。