Split string and number columns - sql

Question

Let's say I have a table such as
ItemID ClassID
------------------------
1 10, 13, 12
2 5, 7
and would like to copy the data to another table like so
ItemID Numbering ClassID
----------------------------------
1 1 10
1 2 13
1 3 12
2 1 5
2 2 7
Separating the comma-delimited ClassID field into individual rows, retaining the order they had in the first table
Populating the Numbering row on insert. The Numbering column has sequential integers for each batch of ClassID and is why ClassID needs to be kept in order.
I have attempted this with the following function:
CREATE FUNCTION dbo.Split
(
#String NVARCHAR(MAX)
)
RETURNS #SplittedValues TABLE(
Value INT
)
AS
BEGIN
DECLARE #SplitLength INT
DECLARE #Delimiter VARCHAR(10)
SET #Delimiter = ','
WHILE len(#String) > 0
BEGIN
SELECT #SplitLength = (CASE charindex(#Delimiter, #String)
WHEN 0 THEN
datalength(#String) / 2
ELSE
charindex(#Delimiter, #String) - 1
END)
INSERT INTO #SplittedValues
SELECT cast(substring(#String, 1, #SplitLength) AS INTEGER)
WHERE
ltrim(rtrim(isnull(substring(#String, 1, #SplitLength), ''))) <> '';
SELECT #String = (CASE ((datalength(#String) / 2) - #SplitLength)
WHEN 0 THEN
''
ELSE
right(#String, (datalength(#String) / 2) - #SplitLength - 1)
END)
END
RETURN
END
but it only partly works. It copies the rows the correct amount of times (i.e. three times for ItemID=1, and twice for ItemID=2 in the above example), but they are exact copies of the row (all saying '10, 13, 12') and the comma-delimited parts are not split up. There is also nothing in the function to add to the Numbering column.
So, I have two questions: How do I modify the above function to split up the ClassID string, and what do I add to correctly increment the Numbering column?
Thanks!

Answer 1

I'd use a recursive CTE to do it.
WITH SplitCTE AS
(
SELECT
itemid,
LEFT(ClassID,CHARINDEX(',',ClassID)-1) AS ClassID
,RIGHT(ClassID,LEN(ClassID)-CHARINDEX(',',ClassID)) AS remaining
FROM table1
WHERE ClassID IS NOT NULL AND CHARINDEX(',',ClassID)>0
UNION ALL
SELECT
itemid,
LEFT(remaining,CHARINDEX(',',remaining)-1)
,RIGHT(remaining,LEN(remaining)-CHARINDEX(',',remaining))
FROM SplitCTE
WHERE remaining IS NOT NULL AND CHARINDEX(',',remaining)>0
UNION ALL
SELECT
itemid,remaining,null
FROM SplitCTE
WHERE remaining IS NOT NULL AND CHARINDEX(',',remaining)=0
)
SELECT
itemid,
row_number() over (partition by itemid order by cast(classid as int) asc) as Numbering,
cast (ClassID as int) as ClassID
FROM
SplitCTE
UNION ALL
select
ItemId,
1,
cast(classid as int)
FROM table1
WHERE ClassID IS NOT NULL AND CHARINDEX(',',ClassID) = 0
SQL Fiddle

Answer 2

DECLARE #t TABLE( ID INT IDENTITY, data VARCHAR(50))
INSERT INTO #t(data) SELECT '10, 13, 12'
INSERT INTO #t(data) SELECT '5, 7'
select F1.id,O.splitdata, ROW_NUMBER() OVER(PARTITION BY ID ORDER BY (SELECT 1))
from (
select *,cast(''+replace(F.data,',','')+'' as XML) as xmlfilter from #t F
)F1
cross apply
(
select fdata.D.value('.','varchar(50)') as splitdata from f1.xmlfilter.nodes('X') as fdata(D)
) O