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Posts Tagged ‘ROWS to CSV’

New built-in function STRING_AGG() with option “WITHIN GROUP” – SQL Server 2017

December 23, 2016 1 comment

 
In one of my [previous post] I discussed about a new function STRING_SPLIT() introduced in SQL Server 2016, which splits a Sentence or CSV String to multiple values or rows.
 

Now with the latest CTP 1.x version of SQL Server vNext (I’m calling it “SQL Server 2017”) a new function is introduced to just do its reverse, i.e. Concatenate string values or expressions separated by any character.

The STRING_AGG() aggregate function takes all expressions from rows and concatenates them into a single string in a single row.

It implicitly converts all expressions to String type and then concatenates with the separator defined.
 

–> In the example below I’ll populate a table with States and Cities in separate rows, and then try to Concatenate Cities belonging to same States:

USE tempdb
GO

CREATE TABLE #tempCityState (
    [State] VARCHAR(5), 
    [Cities] VARCHAR(50)
)
GO

INSERT INTO #tempCityState

SELECT 'CA', 'Hanford'
UNION ALL
SELECT 'CA', 'Fremont'
UNION ALL
SELECT 'CA', 'Los Anggeles'
UNION ALL
SELECT 'CO', 'Denver'
UNION ALL
SELECT 'CO', 'Aspen'
UNION ALL
SELECT 'CO', 'Vail'
UNION ALL
SELECT 'CO', 'Teluride'
UNION ALL
SELECT 'WA', 'Seattle'
UNION ALL
SELECT 'WA', 'Redmond'
UNION ALL
SELECT 'WA', 'Bellvue'
GO

SELECT * FROM #tempCityState

State	Cities
CA	Hanford
CA	Fremont
CA	Los Anggeles
CO	Denver
CO	Aspen
CO	Vail
CO	Teluride
WA	Seattle
WA	Redmond
WA	Bellvue

 

–> To comma separate values under a single row you just need to apply the STRING_AGG() function:

SELECT 
	STRING_AGG(Cities, ', ') as AllCities
FROM #tempCityState

-- Use "WITHIN GROUP (ORDER BY ...)" clause to concatenate them in an Order:
SELECT 
	STRING_AGG(Cities, ', ') WITHIN GROUP (ORDER BY Cities) as AllCitiesSorted
FROM #tempCityState


 

–> Now to Concatenate them by States, you just need to group them by the State, like any other aggregate function:

SELECT 
	State, 
	STRING_AGG(Cities, ', ') as CitiesByStates
FROM #tempCityState
GROUP BY State

-- Use "WITHIN GROUP (ORDER BY ...)" clause to concatenate them in an Order:
	State, 
	STRING_AGG(Cities, ', ') WITHIN GROUP (ORDER BY Cities) as CitiesByStatesSorted
FROM #tempCityState
GROUP BY State


 

You can check more about STRING_AGG() on MSDN.

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Categories: SQL Built-in Functions, SQL Server 2017 Tags: , , , ,

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
Categories: SQL Tips Tags: , , ,