根据另一个 table 填充 ID

Question

我有以下 Table:

以上示例数据如下：

declare @years table (idYear int primary key identity, cYearDescription varchar(20), dYearStartDate datetime)

insert into @years (cYearDescription,dYearStartDate) values
    ('Year 1','2014-08-31')
,   ('Year 2','2015-07-01')
,   ('Year 3','2016-07-01')
,   ('Year 4','2017-07-01')
,   ('Year 5','2018-07-01')
,   ('Year 6','2019-07-01')

select
*
from    @years

注意开始日期，其中 idYear = 1 是该月的月底。我以这种方式提供了样本数据，因为它正是我实际 table...

中的情况

然后我使用此脚本为这些月之间的所有期间生成每个月的月末：

;with cte as
(
select  dateadd(day, nbr - 1, (select min(dYearStartDate) from @years)) CalendarDate
from    ( select    row_number() over ( order by c.object_id ) as nbr
          from      sys.columns c
        ) nbrs
where   nbr - 1 <= datediff(day, (select min(dYearStartDate) from @years), (select max(dYearStartDate) from @years))
)
,   months as (
select
eomonth(CalendarDate)   EndOfMonth
from    cte
group by eomonth(CalendarDate)
)

select
*
from    months

然后我用我的虚拟 table 加入 cte，如下所示：

declare @years table (idYear int primary key identity, cYearDescription varchar(20), dYearStartDate datetime)

insert into @years (cYearDescription,dYearStartDate) values
    ('Year 1','2014-08-31')
,   ('Year 2','2015-07-01')
,   ('Year 3','2016-07-01')
,   ('Year 4','2017-07-01')
,   ('Year 5','2018-07-01')
,   ('Year 6','2019-07-01')


;with cte as
(
select  dateadd(day, nbr - 1, (select min(dYearStartDate) from @years)) CalendarDate
from    ( select    row_number() over ( order by c.object_id ) as nbr
          from      sys.columns c
        ) nbrs
where   nbr - 1 <= datediff(day, (select min(dYearStartDate) from @years), (select max(dYearStartDate) from @years))
)
,   months as (
select
eomonth(CalendarDate)   EndOfMonth
from    cte
group by eomonth(CalendarDate)
)

select
*
from    months m
left join @years y  on  eomonth(dYearStartDate) = EndOfMonth
order by EndOfMonth

以上给出了以下结果：

我该如何操作使其看起来如下所示：

我已经尝试了 rank、ntile 和 row_number，但是 none 给出了我需要的结果...

非常感谢您的帮助！

编辑

我已将上面的 select 更改为以下内容：

select
*
,   isnull(idYear,lag(idYear) over (order by EndOfMonth))   idYear
,   (select idYear from @years where year(dYearStartDate) = year(EndOfMonth))   idYear
from    months m
left join @years y  on  eomonth(dYearStartDate) = EndOfMonth
order by EndOfMonth

但是可以看出，它看起来不像我预期的结果：

Answer 1

您可以尝试通过连接 YEAR(@years.dYearStartDate) 和 YEAR(month.EndOfMonth) 从 @years table 获取每年的信息，如下所示：

select a.EndOfMonth, b.idYear, b.cYearDescription, b.dYearStartDate
 from (
    select year(m.EndOfMonth) curYear, *
       from months m
     left join @years y  
       on  eomonth(dYearStartDate) = EndOfMonth) a
   inner join (select year(dYearStartDate) curYear, * from @years) b
     on a.curYear = b.curYear
   order by EndOfMonth

Answer 2

我解决这个问题的唯一方法是使用 LEAD 向我的 table 添加一个 End Date，这很有效。

话虽如此，我可以查询这些日期之间的 idYear，如下所示：

select
*
,       iif(idYear is null,(select idYear from LeadDateAdded where EndOfMonth between dYearStartDate and dYearEndDate),idYear)  idYear
from    months m
left join LeadDateAdded y   on  eomonth(dYearStartDate) = EndOfMonth
order by EndOfMonth

完整的最终代码如下所示：

declare @years table (idYear int primary key identity, cYearDescription varchar(20), dYearStartDate datetime)

insert into @years (cYearDescription,dYearStartDate) values
    ('Year 1','2014-08-31')
,   ('Year 2','2015-07-01')
,   ('Year 3','2016-07-01')
,   ('Year 4','2017-07-01')
,   ('Year 5','2018-07-01')
,   ('Year 6','2019-07-01')
,   ('Year 7','2020-07-01')


;with cte as
(
select  dateadd(day, nbr - 1, (select min(dYearStartDate) from @years)) CalendarDate
from    ( select    row_number() over ( order by c.object_id ) as nbr
          from      sys.columns c
        ) nbrs
where   nbr - 1 <= datediff(day, (select min(dYearStartDate) from @years), (select max(dYearStartDate) from @years))
)
,   months as (
select
eomonth(CalendarDate)   EndOfMonth
from    cte
group by eomonth(CalendarDate)
)
,   Years as (
select
    idYear
,   cYearDescription
,   dYearStartDate
,   cast(lead(eomonth(dYearStartDate)) over (order by idYear) as datetime)  dYearEndDate
from    @years
)

select
*
,       iif(idYear is null,(select idYear from Years where EndOfMonth between dYearStartDate and dYearEndDate),idYear)  idYear
from    months m
left join Years y   on  eomonth(dYearStartDate) = EndOfMonth
order by EndOfMonth

结果如下（最后一列是我需要的结果）：

根据另一个 table 填充 ID

Populate Id's Based on another table

tsql

sql-server-2017