Break up monthly data into daily

问题

I have budget data for a company in the following montly format. SqlFiddle link here.

Dept#  YearMonth  Budget($)
--------------------------
001    201301     100
001    201302     110
001    201303     105
..     .....      ...
002    201301     200
...    .....      ...

I am required to break this up into daily records, which would look like this:

Dept#  Date       Budget($)
--------------------------
001    20130101     xxx
001    20130102     xxx
001    20130103     xxx
..     .....      ...

I need to generate daily records from each record in the source table. I don't want to assume that each month has 30 days. How do I determine the actual number of days for each month and break it up in the format shown above?

I appreciate any kind of help. Thanks!

回答1:

Try:

with cte as
(select [dept#], [YearMonth], convert(datetime,[YearMonth]+'01',112) [Date], [Budget($)]
 from budget
 union all
 select [dept#], [YearMonth], dateadd(d, 1, [Date]) [Date], [Budget($)]
 from cte
 where datediff(m,[Date],dateadd(d, 1, [Date]))=0
)
select [dept#], [Date], 
       1.0*[Budget($)] / count(*) over (partition by [dept#], [YearMonth]) [DailyBudget($)]
from cte
order by 1,2

(There's an implicit conversion from integer to floating point in the budget, as otherwise the daily rate will be rounded to the nearest dollar - this will not be necessary if the budget datatype is already held as something like numeric(10,2).)

(SQLFiddle here)

来源：https://stackoverflow.com/questions/15639168/break-up-monthly-data-into-daily