SQL: Nested SELECT with multiple values in a single field - sql

Question

In my SQL 2005 DB, I have a table with values stored as IDs with relationships to other tables. So in my MyDBO.warranty table, I'm storing product_id instead of product_name in order to save space. The product_name is stored in MyDBO.products.
When the marketing department pulls the demographic information, the query selects the corresponding name for each ID from related tables (trimmed down for brevity):
SELECT w1.warranty_id AS "No.",
w1.created AS "Register Date"
w1.full_name AS "Name",
w1.purchase_date AS "Purchased",
(
SELECT p1.product_name
FROM WarrDBO.products p1 WITH(NOLOCK)
WHERE p1.product_id = i1.product_id
) AS "Product Purchased",
i1.accessories
FROM WarrDBO.warranty w1
LEFT OUTER JOIN WarrDBO.warranty_info i1
ON i1.warranty_id = w1.warranty_id
ORDER BY w1.warranty_id ASC
Now, my problem is that the "accessories" column on the warranty_info table stores several values:
No. Register Date Name Purchased Accessories
---------------------------------------------------------------------
1500 1/1/2008 Smith, John Some Product 5,7,9
1501 1/1/2008 Hancock, John Another 2,3
1502 1/1/2008 Brown, James And Another 2,9
I need to do something similar with "Accessories" that I did with "Product" and pull accessory_name from the MyDBO.accessories table using accessory_id. I'm not sure where to start, because first I'd need to extract the IDs and then somehow concatenate multiple values into a string. So each line would have "accessoryname1,accessoryname2,accessoryname3":
No. Register Date Name Purchased Accessories
---------------------------------------------------------------------
1500 1/1/2008 Smith, John Some Product Case,Bag,Padding
1501 1/1/2008 Hancock, John Another Wrap,Label
1502 1/1/2008 Brown, James And Another Wrap,Padding
How do I do this?
EDIT>> Posting my final code:
I created this function:
CREATE FUNCTION SQL_GTOInc.Split
(
#delimited varchar(50),
#delimiter varchar(1)
) RETURNS #t TABLE
(
-- Id column can be commented out, not required for sql splitting string
id INT identity(1,1), -- I use this column for numbering splitted parts
val INT
)
AS
BEGIN
declare #xml xml
set #xml = N'<root><r>' + replace(#delimited,#delimiter,'</r><r>') + '</r></root>'
insert into #t(val)
select
r.value('.','varchar(5)') as item
from #xml.nodes('//root/r') as records(r)
RETURN
END
And updated my code accordingly:
SELECT w1.warranty_id,
i1.accessories,
(
CASE
WHEN i1.accessories <> '' AND i1.accessories <> 'NULL' AND LEN(i1.accessories) > 0 THEN
STUFF(
(
SELECT ', ' + a1.accessory
FROM MyDBO.accessories a1
INNER JOIN MyDBO.Split(i1.accessories, ',') a2
ON a1.accessory_id = a2.val
FOR XML PATH('')
), 1, 1, ''
)
ELSE ''
END
) AS "Accessories"
FROM MyDBO.warranty w1
LEFT OUTER JOIN MyDBO.warranty_info i1
ON i1.warranty_id = w1.warranty_id

Answer 1

You could write a table valued function that simply splits comma separated string into XML and turns XML nodes to rows.
See:
http://www.kodyaz.com/articles//t-sql-convert-split-delimeted-string-as-rows-using-xml.aspx
Join to accessories through the result of function call, and stuff the result back to comma separated list of names.
Untested code:
SELECT w1.warranty_id AS "No.",
w1.created AS "Register Date"
w1.full_name AS "Name",
w1.purchase_date AS "Purchased",
(
SELECT p1.product_name
FROM WarrDBO.products p1 WITH(NOLOCK)
WHERE p1.product_id = i1.product_id
) AS "Product Purchased",
STUFF(
(
SELECT
', ' + a.name
FROM [table-valued-function](i1.accessories) acc_list
INNER JOIN accessories a ON acc_list.id = a.id
FOR XML PATH('')
), 1, 1, ''
) AS [accessories]
FROM WarrDBO.warranty w1
LEFT OUTER JOIN WarrDBO.warranty_info i1
ON i1.warranty_id = w1.warranty_id
ORDER BY w1.warranty_id ASC

Answer 2

Nothing to do with your question. Just a note that your original query can also be written, moving the subqery to a join, as:
SELECT w1.warranty_id AS "No.",
w1.created AS "Register Date"
w1.full_name AS "Name",
w1.purchase_date AS "Purchased",
p1.product_name AS "Product Purchased",
i1.accessories
FROM WarrDBO.warranty w1
INNER JOIN WarrDBO.products p1
ON p1.product_id = i1.product_id
LEFT OUTER JOIN WarrDBO.warranty_info i1
ON i1.warranty_id = w1.warranty_id
ORDER BY w1.warranty_id ASC

Answer 3

You just need to use the FOR XML feature of SQL Server to easily cat strings:
Example from the linked blog post:
SELECT
STUFF(
(
SELECT
' ' + Description
FROM dbo.Brands
FOR XML PATH('')
), 1, 1, ''
) As concatenated_string
To parse a field that has already been stored as comma delimited you will have to write a UDF that parses the field and returns a table which can then be used with an IN predicate in your WHERE clause. Look here for starters, and here.

Answer 4

It seem to be a work for a concatenate aggregate function.
In SQL it can be deployed using CLR
http://www.mssqltips.com/tip.asp?tip=2022