Creating Dynamic Pivot Table Column Names - sql-server

Question

I have created a pivot table with hard coded column names. The pivot table simply keeps a rolling sum of sales by qty (current month + 11 months back).
It was my first time using the PIVOT function properly and the code works fine.
SELECT
Item_Code_Desc,
ISNULL([Current],0) AS [Current],
ISNULL([1],0) AS [1],
ISNULL([2],0) AS [2],
ISNULL([3],0) AS [3],
ISNULL([4],0) AS [4],
ISNULL([5],0) AS [5],
ISNULL([6],0) AS [6],
ISNULL([7],0) AS [7],
ISNULL([8],0) AS [8],
ISNULL([9],0) AS [9],
ISNULL([10],0) AS [10],
ISNULL([11],0) AS [11]
FROM
(SELECT
CONCAT(ST.Code,' - ', ST.Description_1) AS Item_Code_Desc,
STT.ActualQuantity AS Qty,
CASE
WHEN MONTH(STT.TxDate) = MONTH(GETDATE()) THEN 'Current'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -1, GETDATE())) THEN '1'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -2, GETDATE())) THEN '2'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -3, GETDATE())) THEN '3'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -4, GETDATE())) THEN '4'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -5, GETDATE())) THEN '5'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -6, GETDATE())) THEN '6'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -7, GETDATE())) THEN '7'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -8, GETDATE())) THEN '8'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -9, GETDATE())) THEN '9'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -10, GETDATE())) THEN '10'
WHEN MONTH(STT.TxDate) = MONTH(DATEADD(MONTH, -11, GETDATE())) THEN '11'
ELSE '0'
END AS [Period]
FROM
_bvSTTransactionsFull AS STT
INNER JOIN
StkItem AS ST ON STT.AccountLink = ST.StockLink
WHERE
STT.TxDate >= DATEADD(MONTH, -11, DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0))
AND STT.Module = 'AR') AS P
PIVOT
(SUM(P.Qty)
FOR P.Period IN ([1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[Current])
) AS PVT
To make the output more dynamic, I wanted to rather show the month and year as the field heading, rather than just the 1,2,3 etc.
To attempt this, I first took out the original CASE, and used the CONCAT function to get the desired result
CONCAT(DATENAME(MONTH,STT.TxDate),' ',YEAR(STT.TxDate)) AS [Period],
Now that the sub-query was showing the transaction date in the format "mmmm yyyy", I wanted the table to pivot on this. I did start wondering how it was going to do this as I was reaching the end, as the column names are not hard coded anymore.
After trying
PIVOT (
SUM(P.Qty)
FOR CONCAT(DATENAME(MONTH,P.TxDate),' ',YEAR(P.TxDate))
) AS PVT
And many other variations I did do some research, and I see this process is slightly more complex than I thought.
I haven't used the STUFF and FOR XML PATH before. I have attempted to convert the above into the examples I have found on the net. But I'm trying in vein as I don't understand the core logic of what I am trying to do.
Please could I have assistance with not only how to get the pivot dynamic, but perhaps some notes to further understand what is happening. Really appreciate some help on this!
After Attempting
This is my attempt to get it right:
DECLARE
#Cols NVARCHAR(MAX),
#Query NVARCHAR(MAX),
#Module NVARCHAR = 'AR'
SELECT
#Cols = STUFF((SELECT DISTINCT ',' + 'CONCAT(DATENAME(MONTH, STT.TxDate),,YEAR(STT.TxDate))' + QUOTENAME(NAME)
FROM _bvSTTransactionsFull AS STT
WHERE STT.Module = 'AR'
FOR XML PATH (''), TYPE).VALUE('.','NVARCHAR(MAX)'),1,1,'')
SELECT
#Query = '
SELECT
Item_Code,
Item_Desc,
' +''''+ #Cols + '''''
FROM
(SELECT
ST.Code AS Item_Code,
ST.Description_1 AS Item_Desc,
STT.ActualQuantity AS Qty,
CONCAT(DATENAME(MONTH, STT.TxDate),,YEAR(STT.TxDate)) AS [Period]
FROM
_bvSTTransactionsFull AS STT
INNER JOIN
StkItem AS ST ON STT.AccountLink = ST.StockLink
WHERE
STT.TxDate >= DATEADD(MONTH, -13, DATEADD(MONTH, DATEDIFF(MONTH, 0,
GETDATE()), 0))
AND STT.Module = '+ #Module +') AS P
PIVOT
(SUM(P.Qty)
FOR P.Period IN ('+#cols+')
) AS PVT '
PRINT #Query
EXEC (#Query)
But I'm getting the following error:
Msg 207, Level 16, State 1, Line 7
Invalid column name 'NAME'.
Where am I off here?

Answer 1

Your result is correct above however, you will not have your columns sorted by the correct date...
The below would cater for that:
DECLARE
#Cols1 VARCHAR(MAX),
#Cols2 VARCHAR(MAX),
#Query VARCHAR(MAX),
#Period VARCHAR(MAX) = -13 ; --/ Select number of months to view back on (excluding current month) \--
declare #tmptbl table (PeriodDate datetime, col1 varchar(100), col2 varchar(100))
insert into #tmptbl (PeriodDate, col1, col2)
SELECT DISTINCT dPeriodDate,'ISNULL('+ QUOTENAME(CONCAT(DATENAME(MONTH, dPeriodDate),' ',YEAR(dPeriodDate)))+',0) AS' + QUOTENAME(CONCAT(DATENAME(MONTH, dPeriodDate),' ',YEAR(dPeriodDate))) col1
, QUOTENAME(CONCAT(DATENAME(MONTH, dPeriodDate),' ',YEAR(dPeriodDate))) col2
FROM _bvSTTransactionsFull AS S join _etblPeriod p on EOMONTH(s.TxDate) = p.dPeriodDate
WHERE S.Module = 'AR' AND S.TxDate > = DATEADD(MONTH, -13, DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0))
SELECT
#Cols1 = STUFF((SELECT ',' + col1
FROM #tmptbl order by PeriodDate
FOR XML PATH (''), TYPE).value('.','NVARCHAR(MAX)'),1,1,'') --/ allows the first SELECT fields to have the ISNULL function and Alias \--
SELECT
#Cols2 = STUFF((SELECT ',' + col2
FROM #tmptbl order by PeriodDate
FOR XML PATH (''), TYPE).value('.','NVARCHAR(MAX)'),1,1,'') --/ becasue of the need for ISNULL above, second #Cols needed for the Pivot (pivot cannot have ISNULL in it) \--
SELECT
#Query =
'SELECT
Item_Code_Desc,
'+#Cols1+'
FROM
(SELECT
CONCAT(ST.Code,'' - '', ST.Description_1) AS Item_Code_Desc,
STT.ActualQuantity AS Qty,
CONCAT(DATENAME(MONTH, STT.TxDate),'' '',YEAR(STT.TxDate)) AS [Period]
FROM
_bvSTTransactionsFull AS STT
INNER JOIN
StkItem AS ST ON STT.AccountLink = ST.StockLink
WHERE
STT.TxDate >= DATEADD(MONTH, '+#Period+', DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0))
AND STT.Module = ''AR'') AS P
PIVOT
(SUM(P.Qty)
FOR P.Period IN ('+#cols2+')
) AS PVT '
PRINT #Query
EXEC (#Query)
I left the changes I made in small caps for you to see the changes...

Answer 2

Solved :)
DECLARE
#Cols1 VARCHAR(MAX),
#Cols2 VARCHAR(MAX),
#Query VARCHAR(MAX),
#Period VARCHAR(MAX) = -12 ; --/ Select number of months to view back on (excluding current month) \--
SELECT
#Cols1 = STUFF((SELECT DISTINCT ',' +'ISNULL('+ QUOTENAME(CONCAT(DATENAME(MONTH, S.TxDate),' ',YEAR(S.TxDate)))+',0) AS' + QUOTENAME(CONCAT(DATENAME(MONTH, S.TxDate),' ',YEAR(S.TxDate)))
FROM _bvSTTransactionsFull AS S
WHERE S.Module = 'AR' AND S.TxDate > = DATEADD(MONTH, -13, DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0))
FOR XML PATH (''), TYPE).value('.','NVARCHAR(MAX)'),1,1,'') --/ allows the first SELECT fields to have the ISNULL function and Alias \--
SELECT
#Cols2 = STUFF((SELECT DISTINCT ',' + QUOTENAME(CONCAT(DATENAME(MONTH, S.TxDate),' ',YEAR(S.TxDate)))
FROM _bvSTTransactionsFull AS S
WHERE S.Module = 'AR' AND S.TxDate > = DATEADD(MONTH, -13, DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0))
FOR XML PATH (''), TYPE).value('.','NVARCHAR(MAX)'),1,1,'') --/ becasue of the need for ISNULL above, second #Cols needed for the Pivot (pivot cannot have ISNULL in it) \--
SELECT
#Query =
'SELECT
Item_Code_Desc,
'+#Cols1+'
FROM
(SELECT
CONCAT(ST.Code,'' - '', ST.Description_1) AS Item_Code_Desc,
STT.ActualQuantity AS Qty,
CONCAT(DATENAME(MONTH, STT.TxDate),'' '',YEAR(STT.TxDate)) AS [Period]
FROM
_bvSTTransactionsFull AS STT
INNER JOIN
StkItem AS ST ON STT.AccountLink = ST.StockLink
WHERE
STT.TxDate >= DATEADD(MONTH, '+#Period+', DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0))
AND STT.Module = ''AR'') AS P
PIVOT
(SUM(P.Qty)
FOR P.Period IN ('+#cols2+')
) AS PVT '
PRINT #Query
EXEC (#Query)