Dynamic SQL Server 2005 Pivot - sql-server-2005

Question

I have worked out how to pivot a row from a table using PIVOT in SQL Server 2005, however, I dont like the method as I have had to hard code the columns (Currency Codes) and I would like to have the Pivot select the columns dynamically.
As an Example, imagine you have the following table (called OrderCash):
OrderID CAD CHF EUR GBP JPY NOK USD
40 0 0 128.6 552.25 -9232 0 -4762
41 0 0 250.2 552.25 -9232 0 -4762
42 233.23 0 552.25 -9232 0 0 -4762
The hard-coded Pivot statement is:
SELECT OrderID,
CurrCode + 'GBP CURNCY' AS Ticker,
Cash AS Position
FROM
(
SELECT OrderID,
CAD,
CHF,
EUR,
GBP,
JPY,
NOK,
USD
FROM OrderCash
) p
UNPIVOT
(
Cash FOR CurrCode IN
(CAD, CHF, EUR, GBP, JPY, NOK, USD)
) AS unpvt
WHERE Cash != 0
And OrderID = 42
This would return the following required table:
OrderID Ticker Position
42 CADGBP CURNCY 233.23
42 EURGBP CURNCY 552.25
42 GBPGBP CURNCY -9232
42 USDGBP CURNCY -4762
The problem arrises further down the road when someone tells me I need to have AUD as a new currency in the table?
FYI, I have a table-valued function that returns all the column names as a table:
ALTER FUNCTION [dbo].[GetTableColumnNames]
(
#TableName NVARCHAR(250),
#StartFromColumnNum INT
)
RETURNS #ReturnTable TABLE
(
ColName NVARCHAR(250)
)
AS
BEGIN
INSERT INTO #ReturnTable
SELECT COLUMN_NAME from information_schema.columns
WHERE TABLE_NAME = #TableName
AND ORDINAL_POSITION >= #StartFromColumnNum
ORDER BY ORDINAL_POSITION
RETURN
END
So the easy bit has been done (SELECT * FROM dbo.GetTableColumnNames('OrderCash',2)), the problem I am having is inserting this 'dynamic' table with the column names into the Pivot?
Any help would be much appreciated.
Many thanks
Bertie.

Answer 1

I've done a few too many of these dynamic queries of late... (my columns shift by client by month). Here's one way to do it--no testing, no debugging, there might be a few bugs to iron out:
DECLARE
#Command nvarchar(max)
,#ColumnList nvarchar(max)
,#OrderId int
,#Debug bit
-- Build a comman-delimited list of the columns
SELECT #ColumnList = isnull(#ColumnLIst + ',', , '') + ColName
from dbo.GetTableColumnNames('OrderCash', 2)
-- Insert the list of columns in two places in your query
SET #Command = replace('
SELECT OrderID,
CurrCode + ‘‘GBP CURNCY’‘ AS Ticker,
Cash AS Position
FROM
(
SELECT OrderID, <#ColumnList>
FROM OrderCash
) p
UNPIVOT
(
Cash FOR CurrCode IN
(<#ColumnList>)
) AS unpvt
WHERE Cash != 0
And OrderID = #OrderId
', '<#ColumnList>', #ColumnList)
-- Always include something like this!
IF #Debug = 1
PRINT #Command
-- Using sp_executeSQL over EXECUTE (#Command) allows you execution
-- plan resuse with parameter passing (this is the part you may need
-- to debug on a bit, but it will work)
EXECUTE sp_executeSQL #Command, N'#OrderId int', #OrderId