SQL - possible pivot issue - sql

Question

I have a table with the following structure
Item Id, Start Date, End Date
1 , 2015-01-01, 2015-06-01
2 , 2015-01-01, 2015-02-01
3 , 2015-03-01, 2015-08-01
4 , 2015-06-01, 2015-10-01
I would like to view results so i will have each month in the column.
Each row will contain the id of the item that is within this month.
Example:
I am asking for all items that are within 2015-01-01 to 2015-03-01.
The results should display, in columns, all the months within that range. So in this case it's 3 columns, Jan Feb and March.
The number of rows will be the total number of items that are within that range BUT each cell should show value of item id only if that item is within range:
example:
2015-01-01, 2015-02-01, 2015-03-01
1 1 1
2 2 NULL
NULL NULL 3

Answer 1

In order to use pivot, you can create a recursive cte get each item id and the list of months it covers, then pivot the cte.
;WITH cte AS
(
SELECT [Item Id], [Start Date], [End Date]
FROM Table1
WHERE [Start Date] BETWEEN '2015-01-01' AND '2015-03-01' --Date Range you want
OR [End Date] BETWEEN '2015-01-01' AND '2015-03-01' --Date Range you want
UNION ALL
SELECT [Item Id], DATEADD(MONTH, 1, [Start Date]), [End Date]
FROM cte
WHERE DATEADD(MONTH, 1, [Start Date]) <= [End Date]
)
SELECT [2015-01-01],[2015-02-01],[2015-03-01] --List of Dates you want
FROM (
SELECT [Item Id] rn, -- need a unique id here to give one row per record
[Item Id],
CONVERT(VARCHAR(10), [Start Date], 120) [Start Date] -- Format date to yyyy-mm-dd
FROM cte
) t
PIVOT
( MAX([Item Id])
FOR [Start Date] IN ([2015-01-01],[2015-02-01],[2015-03-01])
) p

Answer 2

You most likely need to use dynamic SQL.
This is your data:
declare #first date = '20150101';
declare #last date = '20150301';
Create Table #items(ItemId int, StartDate date, EndDate date);
Insert into #items(ItemId, StartDate, EndDate) values
(1, '2015-01-01', '2015-06-01')
, (2, '2015-01-01', '2015-02-01')
, (3, '2015-03-01', '2015-08-01')
, (4, '2015-06-01', '2015-10-01');
You first need to get the range of values and columns:
declare #values varchar(max);
declare #cols varchar(max);
with range(d) as (
Select top(DATEDIFF(month, #first, #last)+1) cast(DATEADD(month, ROW_NUMBER() over(order by (select 0))-1, #first) as varchar(20))
From (
Select 1 From (values(1), (1), (1), (1), (1), (1), (1), (1), (1), (1)) as x1(n)
Cross Join (values(1), (1), (1), (1), (1), (1), (1), (1), (1), (1)) as x2(n)
) as x(n)
)
Select #values = coalesce(''+#values+ ', ', ' ') + '('''+d+''')'
, #cols = coalesce(''+#cols+ ', ', ' ') + '['+left(DATENAME(month, d), 3)+CAST(year(d) as char(4))+']'
From range
;
This basically create a row for each date between #first and #last and concatenate them with parenthesis and commas (#values) or brackets (#cols).
Content in #values and #cols look like this:
#values = ('2015-01-01'), ('2015-02-01'), ('2015-03-01')
#cols = [Jan2015], [Feb2015], [Mar2015]
You then create a SQL script using theses 2 variables:
declare #sql nvarchar(max);
Set #sql = '
Select *
From (
Select i.ItemId, d = left(DATENAME(month, r.d), 3)+CAST(year(r.d) as char(4))
, id = case when r.d >= i.StartDate and r.d <= i.EndDate then i.ItemId end
From (values'+#values+') as r(d)
Cross Join (Select ItemId, StartDate, EndDate From #items
Where (#first >= StartDate and #first <= EndDate) or (#last >= StartDate and #last <= EndDate)
) i
) as dates
Pivot (
min(id)
For d in('+#cols+')
) as piv
';
This is the pivot query.
Created SQL will look like this in this example:
Select *
From (
Select i.ItemId, d = left(DATENAME(month, r.d), 3)+CAST(year(r.d) as char(4))
, id = case when r.d >= i.StartDate and r.d <= i.EndDate then i.ItemId end
From (values ('2015-01-01'), ('2015-02-01'), ('2015-03-01')) as r(d)
Cross Join (Select ItemId, StartDate, EndDate From #items
Where (#first >= StartDate and #first <= EndDate) or (#last >= StartDate and #last <= EndDate)
) i
) as dates
Pivot (
min(id)
For d in( [Jan2015], [Feb2015], [Mar2015])
) as piv
You can finally execute the script:
exec sp_executesql #sql, N'#first date, #last date', #first, #last;
Ouput:
ItemId Jan2015 Feb2015 Mar2015
1 1 1 1
2 2 2 NULL
3 NULL NULL 3

Answer 3

Probably something like....
Select
CASE WHEN EXISTS (SELECT 1 FROM TableName where Month(Start) = 1 AND ItemId = t.ItemId) THEN t.ItemId END AS [2015-01-01]
,CASE WHEN EXISTS (SELECT 1 FROM TableName where Month(Start) = 2 AND ItemId = t.ItemId) THEN t.ItemId END AS [2015-02-01]
,CASE WHEN EXISTS (SELECT 1 FROM TableName where Month(Start) = 3 AND ItemId = t.ItemId) THEN t.ItemId END AS [2015-03-01]
,CASE WHEN EXISTS (SELECT 1 FROM TableName where Month(Start) = 4 AND ItemId = t.ItemId) THEN t.ItemId END AS [2015-04-01]
,CASE WHEN EXISTS (SELECT 1 FROM TableName where Month(Start) = 5 AND ItemId = t.ItemId) THEN t.ItemId END AS [2015-05-01]
,CASE WHEN EXISTS (SELECT 1 FROM TableName where Month(Start) = 6 AND ItemId = t.ItemId) THEN t.ItemId END AS [2015-06-01]
,CASE WHEN EXISTS (SELECT 1 FROM TableName where Month(Start) = 7 AND ItemId = t.ItemId) THEN t.ItemId END AS [2015-07-01]
,CASE WHEN EXISTS (SELECT 1 FROM TableName where Month(Start) = 8 AND ItemId = t.ItemId) THEN t.ItemId END AS [2015-08-01]
,..... and so on..... for all the other months...
from TableName t