How to invert rows and columns using a T-SQL Pivot Table - sql

Question

I have a query that returns one row. However, I want to invert the rows and columns, meaning show the rows as columns and columns as rows. I think the best way to do this is to use a pivot table, which I am no expert in.
Here is my simple query:
SELECT Period1, Period2, Period3
FROM GL.Actuals
WHERE Year = 2009 AND Account = '001-4000-50031'
Results (with headers):
Period1, Period2, Period3
612.58, 681.36, 676.42
I would like for the results to look like this:
Desired Results:
Period, Amount
Jan, 612.58
Feb, 681.36
Mar, 676.42
This is a simple example, but what I'm really after is a bit more comlex than this. I realize I could produce theses results by using several SELECT commands instead. I'm just hoping someone can shine some light on how to accomplish this with a Pivot Table or if there is yet a better way.

Answer 1

For a fixed set of fields, you can use a UNION of select statements, each statement fetching one of the fields. Standard SQL does not provide a way to transpose the result for a variable number of fields, e.g. select * from table.
If MSSQL has an extension which helps (like pivot), I don't know about it.

Answer 2

Try something like this (tested on MSSQL2008):
DECLARE #Data TABLE(Period1 Decimal(5, 2), Period2 Decimal(5, 2), Period3 Decimal(5, 2))
INSERT #Data
VALUES (612.58, 681.36, 676.42)
SELECT Period, Amount
FROM (SELECT Period1 AS Jan, Period2 AS Feb, Period3 AS Mar FROM #Data) AS D
UNPIVOT (Amount FOR Period IN (Jan, Feb, Mar)) AS U
Update
Based on Jeff's comment, how about this:
DECLARE #Actuals TABLE(Account INT, [Year] INT, Period1 Decimal(5, 2), Period2 Decimal(5, 2), Period3 Decimal(5, 2))
INSERT #Actuals VALUES (1, 2010, 612.58, 681.36, 676.42)
INSERT #Actuals VALUES (1, 2009, 512.58, 581.36, 576.42)
SELECT Account, Period, Amount
FROM
(
SELECT a.Account, a.Period1 AS Jan, a.Period2 AS Feb, a.Period3 AS Mar, a1.Period1 AS Jan1, a1.Period2 AS Feb1, a1.Period3 AS Mar1
FROM #Actuals AS a
LEFT OUTER JOIN #Actuals AS a1 ON a.Account = a1.Account AND a1.[Year] = a.[Year] - 1
WHERE a.[Year] = 2010
) AS d
UNPIVOT (Amount FOR Period IN (Jan, Feb, Mar, Jan1, Feb1, Mar1)) AS u
or, with an explicit year column:
DECLARE #Actuals TABLE(Account INT, [Year] INT, Period1 Decimal(5, 2), Period2 Decimal(5, 2), Period3 Decimal(5, 2))
INSERT #Actuals VALUES (1, 2010, 612.58, 681.36, 676.42)
INSERT #Actuals VALUES (1, 2009, 512.58, 581.36, 576.42)
SELECT Account, [Year], Period, Amount
FROM
(
SELECT a.Account, a.[Year], a.Period1 AS Jan, a.Period2 AS Feb, a.Period3 AS Mar
FROM #Actuals AS a WHERE a.[Year] IN (2009, 2010)
) AS d
UNPIVOT (Amount FOR Period IN (Jan, Feb, Mar)) AS u

Answer 3

Check the unnest function, its quite amazing with little overhead. Just add a select query on top of the nested select query and unnest at that point:
SELECT id,
unnest(array['a', 'b', 'c']) AS colname,
unnest(array[a, b, c]) AS thing
FROM foo
ORDER BY id;