CREATE TABLE	#Sample
		(
			theDate DATE PRIMARY KEY CLUSTERED,
			totalDATA XML COLUMN_SET FOR ALL_SPARSE_COLUMNS NULL,
			ColumnName1 VARCHAR(40) SPARSE NULL
		)

-- Read the first file
DECLARE	@Data XML = '<ColumnName1>Peso</ColumnName1>'

-- Insert into target table
INSERT	#Sample
	(
		theDate,
		totalDATA
	)
VALUES	('20110101', @Data)

-- Show the content of current table
SELECT	thedate,
	totalData,
	ColumnName1
FROM	#Sample

-- Now add new columns present in another file
ALTER TABLE	#Sample
ADD		ColumnName2 VARCHAR(40) SPARSE NULL,
		ColumnName3 VARCHAR(40) SPARSE NULL

-- Add content from the new file with new columns
MERGE	#Sample AS tgt
USING	(
		SELECT	'20110101' AS theDate, '<ColumnName1>Peso</ColumnName1><ColumnName3>MVP</ColumnName3>' AS totalDATA UNION ALL
		SELECT	'20110201', '<ColumnName2>SQLTeam</ColumnName2>'
	) AS src ON src.theDate = tgt.theDate
WHEN	MATCHED
		THEN	UPDATE
			SET	tgt.totalData = src.totalData
WHEN	NOT MATCHED BY TARGET
		THEN	INSERT	(
					theDate,
					totalDATA
				)
			VALUES	(
					src.theDate,
					src.totalDATA
				);

-- Display the content of current table
SELECT	theDate,
	totalDATA,
	ColumnName1,
	ColumnName2,
	ColumnName3
FROM	#Sample

DROP TABLE	#Sample