学术期限开始和结束日期

Question

I在1975年至2020年的D_Term维度中，每个学期（春季，夏季，秋季）都​​有学期开始和结束日期。例如：

 2017-01-16  to 2017-05-18  (Spring)   
 2017-06-05 to 2017-08-04  (Summer) 
 2017-08-24  to 2017-12-20  (Fall)

我目前的问题是我需要创建一个化妆表，其中起始和结束期限为：01/01至05/31（春季），夏季期间为06/01至08/31，秋季期限为这是需要反映学年是什么。这个想法是消除两个连续学期之间的学期结束日期（春季）和学期开学日期（夏季）之间的差距。

我不知道如何去做。欢迎任何想法！

谢谢

Answer 1

首先是一点测试数据：

CREATE TABLE #dates (TermStart DATE, TermEnd DATE, Term VARCHAR(20))
INSERT INTO #dates (TermStart, TermEnd, Term)
VALUES ('2017-01-16','2017-05-18','spring'),
('2017-06-05','2017-08-04','summer'),
('2017-08-24','2017-12-20','fall')

然后是解决方案：

SELECT 
    Term
    , TermStart
    , TermEnd
    , NewStart = CASE WHEN LAG(DATEPART(MONTH,DATEADD(DAY,DATEPART(DAY,TermEnd)*-1,DATEADD(MONTH,1,TermEnd)))) OVER (ORDER BY TermStart ASC) = DATEPART(MONTH,TermStart) 
                        THEN DATEADD(MONTH,1,DATEADD(DAY,1,DATEADD(dd,DATEPART(DAY,TermStart)*-1,TermStart)) )
                        ELSE DATEADD(DAY,1,DATEADD(dd,DATEPART(DAY,TermStart)*-1,TermStart)) 
                        END
    , NewEnd = DATEADD(DAY,DATEPART(DAY,TermEnd)*-1,DATEADD(MONTH,1,TermEnd))
FROM #dates

结果：

Term    TermStart   TermEnd     NewStart    NewEnd
------------------------------------------------------
spring  2017-01-16  2017-05-18  2017-01-01  2017-05-31
summer  2017-06-05  2017-08-04  2017-06-01  2017-08-31
fall    2017-08-24  2017-12-20  2017-09-01  2017-12-31

Answer 2

我试过这个，它有效:)

with cte as
(
SELECT 
   New_Academic_Term_Start_DTTM = CASE WHEN Academic_Term_Code like 'SPRING'
                                then 
      concat(year(Academic_Term_Start_DTTM),'-','01','-','01')
                                WHEN Academic_Term_Code like 'SUMMER'
                                then 
      concat(year(Academic_Term_Start_DTTM),'-','06','-','01')
                                WHEN Academic_Term_Code like 'FALL'
                                then 
      concat(year(Academic_Term_Start_DTTM),'-','08','-','21')
                                end 
      from D_Term
)
select   
   convert(datetime2(7),New_Academic_Term_End_DTTM,120) as 
  New_Academic_Term_End_DTTM
   from cte