SQL dynamically pivot and group results - sql-server-2008

Question

I have a table set up like below:
CLIENTNAME MONTHANDYEAR RESOURCE COST
abc JAN2011 res1 1000
abc FEB2011 res1 2000
def JAN2011 res2 1500
def MAR2011 res1 2000
ghi MAR2011 res3 2500
I need an output like below. Months are to be generated dynamically in 3-month intervals. In this case, is there a way to pivot by MONTHANDYEAR as well as group by clientname?
RESOURCE CLIENTNAME JAN2011 FEB2011 MAR2011
res1 abc 1000 1000
res1 def 2000
res2 def 1500
res3 ghi 2500

Answer 1

This is what the PIVOT operator is for:
SELECT
Resource, ClientName,
[JAN2011], [FEB2011], [MAR2011]
FROM
(
SELECT
*
FROM tblname
) AS SourceTable
PIVOT
(
SUM(COST)
FOR MONTHANDYEAR IN ([JAN2011], [FEB2011], [MAR2011])
) AS PivotTable;
Since your months are selected dynamically using #startDate as a base month, you can use the following dynamic query:
DECLARE #startDate datetime
SET #startDate = '2011-01-01'
DECLARE #sql varchar(MAX)
SET #sql = 'SELECT
Resource, ClientName, [' +
REPLACE(SUBSTRING(CONVERT(varchar, #startDate, 13), 4, 8), ' ', '') + '], [' +
REPLACE(SUBSTRING(CONVERT(varchar, DATEADD(MONTH, 1, #startDate), 13), 4, 8), ' ', '') + '], [' +
REPLACE(SUBSTRING(CONVERT(varchar, DATEADD(MONTH, 2, #startDate), 13), 4, 8), ' ', '') + ']
FROM
(
SELECT
*
FROM tblName
) AS SourceTable
PIVOT
(
SUM(COST)
FOR MONTHANDYEAR IN (' +
QUOTENAME(REPLACE(SUBSTRING(CONVERT(varchar, #startDate, 13), 4, 8), ' ', '')) + ', ' +
QUOTENAME(REPLACE(SUBSTRING(CONVERT(varchar, DATEADD(MONTH, 1, #startDate), 13), 4, 8), ' ', '')) + ', ' +
QUOTENAME(REPLACE(SUBSTRING(CONVERT(varchar, DATEADD(MONTH, 2, #startDate), 13), 4, 8), ' ', '')) + ')
) AS PivotTable'
execute(#sql)
working sqlfiddle here

Answer 2

This data transformation can be done with the PIVOT function.
If you know the values, then you can hard-code the monthandyear dates:
select resource,
clientname,
isnull(jan2011, '') Jan2011,
isnull(feb2011, '') Feb2011,
isnull(mar2011, '') Mar2011
from
(
select clientname, monthandyear, resource, cost
from yourtable
) src
pivot
(
sum(cost)
for monthandyear in (Jan2011, Feb2011, Mar2011)
) piv;
See SQL Fiddle with Demo.
But if the dates are unknown, then you will need to use dynamic SQL:
DECLARE #cols AS NVARCHAR(MAX),
#colNames AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #cols = STUFF((SELECT distinct ',' + QUOTENAME(monthandyear)
from yourtable
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
select #colNames = STUFF((SELECT distinct ', isnull(' + QUOTENAME(monthandyear)+', 0) as '+QUOTENAME(monthandyear)
from yourtable
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query = 'SELECT resource, clientname,' + #colNames + ' from
(
select clientname, monthandyear, resource, cost
from yourtable
) x
pivot
(
sum(cost)
for monthandyear in (' + #cols + ')
) p '
execute(#query)
See SQL Fiddle with Demo.
The result of both is:
| RESOURCE | CLIENTNAME | JAN2011 | FEB2011 | MAR2011 |
-------------------------------------------------------
| res1 | abc | 1000 | 2000 | 0 |
| res1 | def | 0 | 0 | 2000 |
| res2 | def | 1500 | 0 | 0 |
| res3 | ghi | 0 | 0 | 2500 |

Answer 3

SELECT Resource, Clientname
, SUM(CASE WHEN MonthAndYear = 'JAN2011' THEN COST ELSE 0 END) AS JAN2011
, SUM(CASE WHEN MonthAndYear = 'FEB2011' THEN COST ELSE 0 END) AS FEB2011
, SUM(CASE WHEN MonthAndYear = 'MAR2011' THEN COST ELSE 0 END) AS MAR2011
FROM yourtable
GROUP BY Resource, Clientname
You can also remove the ELSE 0 to return a NULL value for resource/clientname combinations without data