これが PIVOT 演算子の目的です。
SELECT
Resource, ClientName,
[JAN2011], [FEB2011], [MAR2011]
FROM
(
SELECT
*
FROM tblname
) AS SourceTable
PIVOT
(
SUM(COST)
FOR MONTHANDYEAR IN ([JAN2011], [FEB2011], [MAR2011])
) AS PivotTable;
月は @startDate を基準月として動的に選択されるため、次の動的クエリを使用できます。
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)
ここで作業中のsqlfiddle