Months Between 2 dates for each Project - sql

Question

Hi I am trying to run a query to return a row for each month between 2 dates for each project that I have. See example data:
Project Start End
1 1/1/2015 3/1/2015
2 2/1/2015 4/1/2015
End Data needed:
Project Month
1 1/1/2015
1 2/1/2015
1 3/1/2015
2 2/1/2015
2 3/1/2015
2 4/1/2015
I have several projects and will need a query to do this for all of them at the same time. How can I do this in SQL Server?

Answer 1

Another option is a CROSS APPLY with an ad-hoc tally table
Select A.Project
,Month = B.D
From YourTable A
Cross Apply (
Select Top (DateDiff(MONTH,A.Start,A.[End])+1) D=DateAdd(Month,-1+Row_Number() Over (Order By(Select null)),A.Start)
From master..spt_values
) B
Returns
Project Month
1 2015-01-01
1 2015-02-01
1 2015-03-01
2 2015-02-01
2 2015-03-01
2 2015-04-01

Answer 2

This is simple if you have or create a table for Months:
create table dbo.Months([Month] date primary key);
declare #StartDate date = '20100101'
,#NumberOfYears int = 30;
insert dbo.Months([Month],MonthEnd)
select top (12*#NumberOfYears)
[Month] = dateadd(month, row_number() over (order by number) -1, #StartDate)
from master.dbo.spt_values;
If you really do not want to have a Months table, you can use a cte like this:
declare #StartDate date = '20100101'
,#NumberOfYears int = 10;
;with Months as (
select top (12*#NumberOfYears)
[Month] = dateadd(month, row_number() over (order by number) -1, #StartDate)
from master.dbo.spt_values
)
Then query it like so:
select
t.Project
, m.Month
from t
inner join dbo.Months m
on m.Month >= t.Start
and m.Month <= t.[End]
rextester demo: http://rextester.com/SXPX26360
returns:
+---------+------------+
| Project | Month |
+---------+------------+
| 1 | 2015-01-01 |
| 1 | 2015-02-01 |
| 1 | 2015-03-01 |
| 2 | 2015-02-01 |
| 2 | 2015-03-01 |
| 2 | 2015-04-01 |
+---------+------------+
calendar and numbers tables reference:
Generate a set or sequence without loops 2- Aaron Bertrand
Creating a Date Table/Dimension in SQL Server 2008 - David Stein
Calendar Tables - Why You Need One - David Stein
Creating a date dimension or calendar table in SQL Server - Aaron Bertrand
TSQL Function to Determine Holidays in SQL Server - Tim Cullen
F_TABLE_DATE - Michael Valentine Jones

Answer 3

I personally like a tally table for this kind of thing. It is the swiss army knife of t-sql.
I create a view on my system for this. If you don't want to create a view you can easily use these ctes anytime you need a tally table.
create View [dbo].[cteTally] as
WITH
E1(N) AS (select 1 from (values (1),(1),(1),(1),(1),(1),(1),(1),(1),(1))dt(n)),
E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
cteTally(N) AS
(
SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
)
select N from cteTally
GO
Now we just need your sample data in a table.
create table #Projects
(
Project int
, Start datetime
, EndDate datetime
)
insert #Projects
select 1, '1/1/2015', '3/1/2015' union all
select 2, '2/1/2015', '4/1/2015'
At this point we get to the real issue here which is retrieving your information. With the sample data and the view this becomes pretty simple.
select p.*
, NewMonth = DATEADD(MONTH, t.N - 1, p.Start)
from #Projects p
join cteTally t on t.N <= DATEDIFF(MONTH, p.Start, p.EndDate) + 1
order by p.Project
, t.N

Answer 4

Generate Time series take help from the link.
Then join time using between
SELECT --something
FROM table1 a
/type of/ JOIN table2 b ON b.field2 BETWEEN a.field2 AND a.field3