Sub CTE or Nested Model - sql

Question

I have a string variable with month and year. This can be multiple seperated with comma. I need to get all the dates of all months in the string
Eg: IF my String have '2014-01,2014-02' I need to return 01-01-2014, 02-01-2014 etc like all days in january and also all dates in february.
I tried like below
DECLARE #myString as NVARCHAR(2000) = '2014-03,2014-04'
;with cte1
as (
SELECT
CAST(
CAST(SUBSTRING(Data, 0, 5) AS VARCHAR(4)) +
RIGHT('0' + CAST(SUBSTRING(Data, 6, 2) AS VARCHAR(2)), 2) +
RIGHT('0' + CAST(1 AS VARCHAR(2)), 2)
AS DATE) AS StartDate
,CONVERT(DATE,DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,CAST(
CAST(SUBSTRING(Data, 0, 5) AS VARCHAR(4)) +
RIGHT('0' + CAST(SUBSTRING(Data, 6, 2) AS VARCHAR(2)), 2) +
RIGHT('0' + CAST(1 AS VARCHAR(2)), 2)
AS DATETIME))+1,0))) AS EndDate
FROM dbo.Split(myString , ',')
),
cte2
AS
(
SELECT StartDate, EndDate FROM cte1
UNION ALL
SELECT CONVERT(DATE, DATEADD(DAY,1 , StartDate)), CONVERT(DATE, DATEADD(DAY,1 , StartDate)) FROM cte2
WHERE CONVERT(DATE, DATEADD(DAY,1 , StartDate)) < EndDate
)
SELECT * FROM cte2
In the first cte i will return 2 rows with start date of the month and end date of the month. So i need to loop all the days in each row of the first cte
I have the work around with 2 seperate queries
-- To get the month start and end date
;with cte1
as (
SELECT
CAST(
CAST(SUBSTRING(Data, 0, 5) AS VARCHAR(4)) +
RIGHT('0' + CAST(SUBSTRING(Data, 6, 2) AS VARCHAR(2)), 2) +
RIGHT('0' + CAST(1 AS VARCHAR(2)), 2)
AS DATE) AS StartDate
,CONVERT(DATE,DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,CAST(
CAST(SUBSTRING(Data, 0, 5) AS VARCHAR(4)) +
RIGHT('0' + CAST(SUBSTRING(Data, 6, 2) AS VARCHAR(2)), 2) +
RIGHT('0' + CAST(1 AS VARCHAR(2)), 2)
AS DATETIME))+1,0))) AS EndDate
FROM dbo.Split(#CompareMonths, ',')
)
--To get all days between start and end date (Current month)
Declare #startdate date = CONVERT(DATE, DATEADD(dd, -DAY(DATEADD(MONTH, 0, GETDATE())) + 1, DATEADD(MONTH, 0, GETDATE())))
Declare #endDate date = DATEADD(DAY, -DAY(DATEADD(MONTH, 1, GETDATE())), DATEADD(MONTH, 1, GETDATE()))
;With cte
as
(
SELECT #startdate sDate
UNION All
SELECT DATEADD(day,1,sDate) FROM cte WHERE DATEADD(day,1,sDate) <= #endDate
)
select * from cte
I need to join this 2 concepts so that from the string i got all the days of all the months i passed

Answer 1

With the help of a numbers table and a splistring function.
SQL Fiddle
MS SQL Server 2012 Schema Setup:
create table dbo.Number(N int primary key);
go
insert into dbo.Number(N)
select top(11000) row_number() over(order by 1/0) - 1
from sys.all_objects as o1, sys.all_objects as o2
go
create function [dbo].[SplitString](#List nvarchar(max), #Delimiter nvarchar(255)) returns table
with schemabinding
as
return
(
select substring(#List, N, charindex(#Delimiter, #List + #Delimiter, N) - N) as Item
from dbo.Number
where N <= convert(int, len(#List)) and
substring(#Delimiter + #List, N, len(#Delimiter)) = #Delimiter
);
Query 1:
declare #S nvarchar(max) = '2014-01,2014-02'
select T2.D
from dbo.SplitString(#S, N',') as S
cross apply (select cast(S.Item+'-01' as date)) as T1(D)
cross apply (
select dateadd(day, N.N, T1.D)
from Number as N
where N between 0 and datediff(day, T1.D, eomonth(T1.D))
) as T2(D)
Results:
| D |
|------------|
| 2014-01-01 |
| 2014-01-02 |
| 2014-01-03 |
| 2014-01-04 |
| 2014-01-05 |
| 2014-01-06 |
| 2014-01-07 |
| 2014-01-08 |
| 2014-01-09 |
| 2014-01-10 |
| 2014-01-11 |
| 2014-01-12 |
| 2014-01-13 |
| 2014-01-14 |
| 2014-01-15 |
| 2014-01-16 |
| 2014-01-17 |
| 2014-01-18 |
| 2014-01-19 |
| 2014-01-20 |
| 2014-01-21 |
| 2014-01-22 |
| 2014-01-23 |
| 2014-01-24 |
| 2014-01-25 |
| 2014-01-26 |
| 2014-01-27 |
| 2014-01-28 |
| 2014-01-29 |
| 2014-01-30 |
| 2014-01-31 |
| 2014-02-01 |
| 2014-02-02 |
| 2014-02-03 |
| 2014-02-04 |
| 2014-02-05 |
| 2014-02-06 |
| 2014-02-07 |
| 2014-02-08 |
| 2014-02-09 |
| 2014-02-10 |
| 2014-02-11 |
| 2014-02-12 |
| 2014-02-13 |
| 2014-02-14 |
| 2014-02-15 |
| 2014-02-16 |
| 2014-02-17 |
| 2014-02-18 |
| 2014-02-19 |
| 2014-02-20 |
| 2014-02-21 |
| 2014-02-22 |
| 2014-02-23 |
| 2014-02-24 |
| 2014-02-25 |
| 2014-02-26 |
| 2014-02-27 |
| 2014-02-28 |
Ref: Split strings the right way – or the next best way