Comments on: Concatenating child rows in SQL – Cross Apply / FOR XML PATH

By: Ryan

Ryan — Wed, 10 Apr 2013 14:32:34 +0000

Great tip Oscar, thanks!

By: Oscar

Oscar — Wed, 10 Apr 2013 14:21:09 +0000

to get rid of the comma you can use STUFF… in Ryan’s example you would basically declare your columns and ‘STUFF’ the one with the results of the CROSS APPLY like this:

SELECT OrderID, OrderNotes, STUFF(listOfLineNotes,1,1,”) as listOfLineNotes
FROM orders AS o
CROSS APPLY (
SELECT linenotes + ‘,’
FROM orderLines AS ol
WHERE ol.orderID = o.orderID
FOR XML PATH(”) )
temp ( listOfLineNotes )

By: Ryan

Ryan — Sun, 02 Jan 2011 04:39:47 +0000

In reply to Bryan. You might be able to use the Left() function to remove the trailing comma character. I don't have my database up now so I can't test it, but something like Left( [computed value], Len([computed value])-1)

By: Bryan

Bryan — Thu, 30 Dec 2010 20:04:07 +0000

Thanks for posting this. It was exactly what I needed!

One minor question though: Is there a way within the query itself to strip the comma off of the last item? For example, when I run the query you posted I get the value "ABC,XYZ," instead of "ABC,XYZ" for the listOfLineNotes field in the first row.

By: Bill Richard

Bill Richard — Fri, 05 Nov 2010 20:05:59 +0000

Interesting, I had no idea you could use CROSS APPLY like that. Thanks

By: Ryan

Ryan — Sat, 23 Oct 2010 14:13:16 +0000

Good stuff Julian, thanks.

By: Julian Halliwell

Julian Halliwell — Sat, 23 Oct 2010 07:50:14 +0000

In MySQL you can accomplish the same in a slightly more transparent way with GROUP_CONCAT. As you say great for any time you need to de-normalise such as populating a search index.

SELECT
o.orderID
,o.orderNotes
,GROUP_CONCAT( lineNotes ) AS listOfLineNotes
FROM
orders o
LEFT JOIN
orderLines ol ON ol.orderID = o.orderID
GROUP BY
o.orderID

By: damiththa

damiththa — Wed, 20 Oct 2010 18:50:46 +0000

Thank you Ryan this is great.
I always wondered how this can be accomplished but now I know how.