SQL operations on all columns of a table - sql

Question

I have many (>48) columns in one table, each column corresponds to a month and contains sales for that month. I need to create another table in which each column equals the addition of the previous 12 columns, e.g. getting the "rolling year" figure, so that e.g. July 2010 has everything from August 2009 through July 2010 added, August 2010 has everything from September 2009 through August 2010, and so on.
I could write this as:
select
[201007TOTAL] = [200908] + [200909] + ... + [201007]
,[201008TOTAL] = [200909] + ... + [201008]
...
...
into #newtable
from #mytable
I was wondering if there was a smarter way of doing this, either creating these as new columns in the table in one step, or perhaps pivoting the data, doing something to it, and re-pivoting?

Answer 1

Altough everybody is right, a different database set-up would be best, I thought this was a nice problem to play around with. Here's my setup:
CREATE TABLE TEST
(
ID INT
, [201401] decimal(19, 5)
, [201402] decimal(19, 5)
, [201403] decimal(19, 5)
, [201404] decimal(19, 5)
, [201405] decimal(19, 5)
, [201406] decimal(19, 5)
, [201407] decimal(19, 5)
)
INSERT INTO TEST
VALUES (1, 1, 2, 3, 4, 5, 6, 7)
Just one record with data is enough to test.
On the assumption the columns to be summed are consecutive in the table, and the first one is the first with datatype decimal. In other words, the table 'starts' (for want of better word) with a PK, which is usually INT, may be followed by descriptions or whatever, followed by the monthly columns to be summed:
DECLARE #OP_START INT
, #OP_END INT
, #LOOP INT
, #DATE VARCHAR(255)
, #SQL VARCHAR(MAX) = 'SELECT '
, #COLNAME VARCHAR(MAX)
-- Set Date to max date (=columnname)
SET #DATE = '201406'
-- Find Last attribute
SET #OP_END = (
SELECT MAX(ORDINAL_POSITION)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'TEST'
AND COLUMN_NAME <= #DATE
)
-- Find First attribute
SET #OP_START = (
SELECT MIN(ORDINAL_POSITION)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'TEST'
AND DATA_TYPE = 'DECIMAL'
)
SET #LOOP = #OP_START
-- Loop through the columns
WHILE #LOOP <= #OP_END
BEGIN
SET #COLNAME = (
SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'TEST'
AND ORDINAL_POSITION = #LOOP
)
-- Build SQL with found ColumnName
SET #SQL = #SQL + '[' + #COLNAME + ']' + '+'
SET #LOOP = #LOOP + 1
END
-- Remove last "+"
SET #SQL = SUBSTRING(#SQL, 1, LEN(#SQL) - 1)
-- Complete SQL
SET #SQL = #SQL + ' FROM TEST'
-- Execute
EXEC(#SQL)
This should keep adding up the monthly values, regardless how many you add. Just change the max date to what pleases you.
I'm NOT saying this is the best way to go, but it is a fun way :P