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Archive for September 16, 2010

Combine multiple ROWS to CSV String… and vice-versa

September 16, 2010 16 comments

There are times when you want to combine values from multiple rows of a single column into a CSV (Comma Separates Value) String.

Like combining multiple orders of each customer into one single row, or multiple Cities against each State as shown below.

It was a bit difficult to do in SQL Server 2000 and requires to create a customized function or a script.

But with SQL Server’s 2005 version, the new “PATH” mode with “FOR XML” provides us a way to get the desired output. Its a bit tricky but will do the needful, that’s why I’ve also added this post for my reference as well.

CREATE TABLE #tempCityState (State VARCHAR(5), City VARCHAR(50))

INSERT INTO #tempCityState
SELECT 'CO', 'Denver' UNION
SELECT 'CO', 'Teluride' UNION
SELECT 'CO', 'Vail' UNION
SELECT 'CO', 'Aspen' UNION
SELECT 'CA', 'Los Angeles' UNION
SELECT 'CA', 'Hanford' UNION
SELECT 'CA', 'Fremont' UNION
SELECT 'WA', 'Seattle' UNION
SELECT 'WA', 'Redmond' UNION
SELECT 'WA', 'Bellvue'

SELECT * FROM #tempCityState
State	City
CA	Hanford
CA	Fremont
CA	Los Angeles
CO	Denver
CO	Aspen
CO	Vail
CO	Teluride
WA	Seattle
WA	Redmond
WA	Bellvue

 

Using the “FOR XML PATH” syntax:

SELECT DISTINCT State, (SELECT SUBSTRING((SELECT ',' + City
 FROM #tempCityState
 WHERE State  = t.State
 FOR XML PATH('')),2,200000)) AS Cities
INTO #tempCityStateCSV
FROM #tempCityState t

-- OR --

SELECT DISTINCT State, (SELECT STUFF((SELECT ',' + City
 FROM #tempCityState
 WHERE State  = t.State
 FOR XML PATH('')),1,1,'')) AS Cities
FROM #tempCityState t

SELECT * FROM #tempCityStateCSV
State	Cities
CA	Hanford,Fremont,Los Angeles
CO	Denver,Aspen,Vail,Teluride
WA	Seattle,Redmond,Bellvue

 

Now, converting it back to multiple rows:

SELECT A.[State], Split.a.value('.', 'VARCHAR(100)') AS City
FROM (SELECT [State], CAST ('<M>' + REPLACE([Cities], ',', '</M><M>') + '</M>' AS XML) AS String
	FROM  #tempCityStateCSV) AS A
CROSS APPLY String.nodes ('/M') AS Split(a)
ORDER BY 1,2
State	City
CA	Fremont
CA	Hanford
CA	Los Angeles
CO	Aspen
CO	Denver
CO	Teluride
CO	Vail
WA	Bellvue
WA	Redmond
WA	Seattle


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