February 17, 2013 at 10:53 pm
Hi -
I am having trouble writing a query to get the distinct values of a column grouping into a single column. Please see the example below:
Data:
Store Name | Category | Product | Color
My Store | Clothing | Awesome Shirt | White
My Store | Clothing | Awesome Shirt | Green
My Store | Clothing | Awesome Shirt | Blue
My Store | Cars | Chevy Impala | White
My Store | Cars | Chevy Impala | Black
My Store | Cars | Chevy Impala | Grey
Desired Result:
My Store | Clothing | Awesome Shirt | WhiteGreenBlue
My Store | Cars | Chevy Impala | WhiteBlackGrey
Thanks for your help!
February 18, 2013 at 1:05 am
February 18, 2013 at 2:34 am
SQLFiddle (link) showing the following solution:
DECLARE @data AS TABLE
(
StoreName varchar(50) NOT NULL,
Category varchar(50) NOT NULL,
Product varchar(50) NOT NULL,
Color varchar(50) NOT NULL,
PRIMARY KEY (StoreName, Category, Product, Color)
);
INSERT @data
(StoreName, Category, Product, Color)
VALUES
('My Store', 'Clothing', 'Awesome Shirt', 'White'),
('My Store', 'Clothing', 'Awesome Shirt', 'Green'),
('My Store', 'Clothing', 'Awesome Shirt', 'Blue'),
('My Store', 'Cars', 'Chevy Impala', 'White'),
('My Store', 'Cars', 'Chevy Impala', 'Black'),
('My Store', 'Cars', 'Chevy Impala', 'Grey');
SELECT
d.StoreName,
d.Category,
d.Product,
Colors =
(
SELECT
d2.Color AS [text()]
FROM @data AS d2
WHERE
d2.StoreName = d.StoreName
AND d2.Category = d.Category
AND d2.Product = d.Product
ORDER BY
d2.Color
FOR XML
PATH (''), TYPE
).value('.[1]', 'varchar(MAX)')
FROM @data AS d
GROUP BY
d.StoreName,
d.Category,
d.Product
ORDER BY
d.StoreName,
d.Category,
d.Product;
Paul White
SQLPerformance.com
SQLkiwi blog
@SQL_Kiwi
February 18, 2013 at 6:54 am
Thank you both, this is very helpful!
February 19, 2013 at 12:35 am
dgowrij (2/19/2013)
Could you please clarify what the below statement actually does?
.value('.[1]', 'varchar(MAX)')Especially the '.[1]'
The value XML method is documented in Books Online:
http://msdn.microsoft.com/en-us/library/ms178030.aspx
The '.[1]' is an XQuery expression, where the '.' is a path expression containing an axis step and a node test:
http://msdn.microsoft.com/en-us/library/ms190451.aspx
More precisely the '.' is approximate shorthand for the axis step and node test, self::node():
http://msdn.microsoft.com/en-us/library/ms191460.aspx
The [1] is a predicate:
http://msdn.microsoft.com/en-us/library/ms177470.aspx
The XML value method requires a single value as input, hence the technical need for the predicate [1].
Paul White
SQLPerformance.com
SQLkiwi blog
@SQL_Kiwi
February 20, 2013 at 11:56 am
One possible modification that you might want to make is to change this:
d2.Color AS [text()]
to this:
d2.Color AS [data()]
That way your items would have a space between them instead of being run together in a continuous string.
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