如何为日期范围内的每个月创建新行？

Question

我需要创建一个视图，为日期范围内的每个月创建新行。我的预订 table 的数据示例如下所示。

Booking ID  Booking Name   Start Date  End Date    Booked Days
1           HolidayUSA     1/01/2020   15/02/2020  46
2           HolidayEurope  20/01/2020  10/03/2020  50
3           HolidayUK      14/03/2020  19/03/2020  5

我想创建一个视图，为日期范围内的每个月添加一条新记录，根据该月的天数计算预订天数，并添加 month/year 个字段。

预期输出：

我正在使用 Microsoft SQL 服务器。任何帮助将不胜感激。

Answer 1

这是我最接近的近似值：

declare @tb table  ([Booking Id] int, [Booking Name] varchar(30),
                    [Start Date] datetime, [End Date] datetime)
-- Sample data
insert @tb values
    (1, 'HolidayUSA','20200101','20200215'),
    (2, 'HolidayEUROPE','20200120','20200310'),
    (3, 'HolidayUK','20200314','20200319')

-- Showing sample data
select *, dateDiff(dd, [Start Date], [End Date]) [Booked Days]
from @tb

declare @dd smallint
select @dd = max(dateDiff(dd, [Start Date], [End Date])) from @tb

with day_cte as (
    select 1 as nbd union all
    select nbd + 1 from day_cte where nbd <= @dd)
select [Booking Id], [Booking Name], [Start Date], [End Date]
    , datePart(yy, dateAdd(dd, nbd, [Start Date])) [Year]
    , left(dateName(mm, dateAdd(dd, nbd, [Start Date])), 3) [Month]
    , count(*) [Booked Days]
from @tb, day_cte
where nbd <= dateDiff(dd, [Start Date], [End Date])
group by [Booking Id], [Booking Name], [Start Date], [End Date]
    , datePart(yy, dateAdd(dd, nbd, [Start Date]))
    , dateName(mm, dateAdd(dd, nbd, [Start Date]))

Answer 2

这是一个基于计数或数字 table 的方法。理货 CTE 创建一个序列（最多 12^4 或 20,736 天（可以增加到任何必要的天数））以按天延长日历。然后按月汇总。

;with
n(n) as (select * from (values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12)) v(n)),
tally_cte(N) as (
     select row_number() over (order by (select null)) 
     from n n1 cross join n n2 cross join n n3 cross join n n4)
select booking_id, booking_name, start_dt, end_dt, dfp.dfp,
       year(dt.booking_dt) [Year], convert(char(3), dt.booking_dt, 0) [Month],
       count(*) booked_days
from #test t
     cross apply
     (select dateadd(d, n-1, t.start_dt) booking_dt 
      from tally_cte
      where n<=datediff(d, t.start_dt, t.end_dt)) dt
     cross apply
     (select datefromparts(year(dt.booking_dt), month(dt.booking_dt), 1) dfp) dfp
group by booking_id, booking_name, start_dt, end_dt, dfp.dfp,
       year(dt.booking_dt), convert(char(3), dt.booking_dt, 0)
order by 1, 3, 5;

输出

booking_id          booking_name    start_dt    end_dt  dfp Year    Month   booked_days
1   HolidayUSA      2020-01-01      2020-02-15  2020-01-01  2020    Jan     31
1   HolidayUSA      2020-01-01      2020-02-15  2020-02-01  2020    Feb     14
2   HolidayEurope   2020-01-20      2020-03-10  2020-01-01  2020    Jan     12
2   HolidayEurope   2020-01-20      2020-03-10  2020-02-01  2020    Feb     29
2   HolidayEurope   2020-01-20      2020-03-10  2020-03-01  2020    Mar     9
3   HolidayUK       2020-03-14      2020-03-19  2020-03-01  2020    Mar     5

如何为日期范围内的每个月创建新行？

How to create new rows for each month within a date range?

sql-server

calendar

date

record

range