Dynamic SQL Pivot Query with Union All - sql-server

Question

I have a static pivot query that tracks historical pricing (see below); it is union all of one table of current data, one table of historical data, and one related table.
I would like to convert it to a dynamic SQL pivot query so that I don't manually have to update the column heading dates all of the time, but I am having problems doing so. The data comes out of an accounting system (Microsoft Dynamics) running on SQL Server, and due to system limitations, I am unable to use ansi nulls/ paddings/ warnings and also unable to use quoted identifiers. Is there another way to create a dynamic sql pivot query?
Here is my current query. I want to replace the month-end dates with dynamic sql. I have view access to the data only.
SELECT ACTDESCR AS "ACCT NAME", concat(right(actnumbr_2,2), actnumbr_3) as PLU, [3/31/2015], [2/28/2015], [1/31/2015], [12/31/2015], [11/30/2014], [10/31/2014], [9/30/2014], [8/31/2014], [7/31/2014], [6/30/2014], [5/31/2014], [4/30/2014], [3/31/2014], [2/28/2014], [1/31/2014]
FROM
(SELECT A.ACTDESCR, EOMONTH(DATEFROMPARTS(B.YEAR1,B.PERIODID,1),0) AS DATE1, A.actnumbr_2, a.actnumbr_3, B.PERDBLNC, A.ACTNUMBR_1
FROM TEST.dbo.table1 AS A
LEFT OUTER JOIN TEST.dbo.TABLE2 AS b
ON (a.ACTINDX = b.ACTINDX)
UNION ALL
SELECT A.ACTDESCR, EOMONTH(DATEFROMPARTS(C.YEAR1,C.PERIODID,1),0) AS DATE1, A.actnumbr_2, a.actnumbr_3, C.PERDBLNC, A.ACTNUMBR_1
FROM TEST.dbo.TABLE1 AS A
LEFT OUTER JOIN TEST.dbo.TABLE3 AS C
ON (a.ACTINDX = C.ACTINDX)
) AS ST
PIVOT
(
SUM(PERDBLNC)
FOR DATE1 IN ([3/31/2015], [2/28/2015], [1/31/2015], [12/31/2015], [11/30/2014], [10/31/2014], [9/30/2014], [8/31/2014], [7/31/2014], [6/30/2014], [5/31/2014], [4/30/2014], [3/31/2014], [2/28/2014], [1/31/2014])
) AS PVT
WHERE ACTNUMBR_1 = ?

Answer 1

You can use T-SQL with dynamic SQL for this:
--VARIABLE TO HOLD DATES--
DECLARE #DATES NVARCHAR(500)
--VARIABLE TO HOLD CODE--
DECLARE #SQL NVARCHAR(MAX)
--TEMP TABLE TO FIND DISTINCT DATES--
CREATE #DATES (COLUMNVALS NVARCHAR(10))
--INSERT DISTINCT DATES INTO TEMP TABLE--
INSERT INTO #DATES
SELECT DISTINCT DATE1 FROM (
SELECT EOMONTH(DATEFROMPARTS(YEAR1,PERIODID,1),0) AS DATE1
FROM TEST.DBO.TABLE2
UNION ALL
SELECT EOMONTH(DATEFROMPARTS(YEAR1,PERIODID,1),0) AS DATE1
FROM TEST.DBO.TABLE3)
--CONCAT DATES INTO SELECT LIST--
SET #DATES = COALESCE(#DATES+', ','') + '[' + DATE1 + ']' FROM #DATES
--CREATE THE SELECT STATEMENT--
SELECT #SQL = '
;WITH ST AS (
SELECT A.ACTDESCR, EOMONTH(DATEFROMPARTS(B.YEAR1,B.PERIODID,1),0) AS DATE1, A.ACTNUMBR_2, A.ACTNUMBR_3, B.PERDBLNC, A.ACTNUMBR_1
FROM TEST.DBO.TABLE1 AS A
LEFT OUTER JOIN TEST.DBO.TABLE2 AS B
ON A.ACTINDX = B.ACTINDX
UNION ALL
SELECT A.ACTDESCR, EOMONTH(DATEFROMPARTS(C.YEAR1,C.PERIODID,1),0) AS DATE1, A.ACTNUMBR_2, A.ACTNUMBR_3, C.PERDBLNC, A.ACTNUMBR_1
FROM TEST.DBO.TABLE1 AS A
LEFT OUTER JOIN TEST.DBO.TABLE3 AS C
ON A.ACTINDX = C.ACTINDX)
SELECT ACTDESCR AS "ACCT NAME", CONCAT(RIGHT(ACTNUMBR_2,2), ACTNUMBR_3) AS PLU, '+#DATES+'
FROM ST
PIVOT
(
SUM(PERDBLNC)
FOR DATE1 IN ('+#DATES+')
) AS PVT
WHERE ACTNUMBR_1 = ?'
--PRINT IT TO SEE WHAT IT'S DONE--
PRINT #SQL
--EXECUTE IT--
EXEC (#SQL)