SQL, Split by 1 column and duplicate other columns - sql-server

Question

Good day!
Maybe you can help me, or tell me if what I want to do is impossible or totally wrong...
I was trying to create a sqlfiddle but it seems the page is down at the moment.
(SQL Server 2008) I have a table, lets say that it has 3 columns, but the person who designed it didn't normalize, so one column holds multiple values, it's something like this:
IdCol Col1 Col2 Col3
1 a1 b1 a, b, c
2 a2 b2 d, e, f
As you can see, Col3 holds multiple values separated by ","
what I want to achieve, is to create a view (can't modify the table because they won't allow me to modify the application) that is something similar to this:
NewIdCol IdCol Col1 Col2 Col3
1 1 a1 b1 a
2 1 a1 b1 b
3 1 a1 b1 c
4 2 a2 b2 d
5 2 a2 b2 e
6 2 a2 b2 f
So the final result has Col3 values split into a different row and every other column's value copied. (the actual table has about 20 columns, and 2 of those columns hold multiple values, so I would need to do it for both columns)
At first I thought it would be easy... but then I hit a block on how to split that string... first I thought about using a split function, but then I didn't know how to join it back with the rest of the columns...
Thanks in advance.

Answer 1

You need to have a function for splitting comma-delimited strings into separate rows. Then you call the function like this:
SELECT
NewIdCol = ROW_NUMBER() OVER(ORDER BY t.IdCol, x.ItemNumber),
t.IdCol,
t.Col1,
t.Col2,
x.Item
FROM Test t
CROSS APPLY [dbo].[DelimitedSplit8K](t.Col3, ',') x
Here is the DelimitedSplit8K function by Jeff Moden.
CREATE FUNCTION [dbo].[DelimitedSplit8K](
#pString NVARCHAR(4000), #pDelimiter NCHAR(1)
)
RETURNS TABLE WITH SCHEMABINDING AS
RETURN
WITH E1(N) AS (
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
)
,E2(N) AS (SELECT 1 FROM E1 a, E1 b)
,E4(N) AS (SELECT 1 FROM E2 a, E2 b)
,cteTally(N) AS(
SELECT TOP (ISNULL(DATALENGTH(#pString),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
)
,cteStart(N1) AS(
SELECT 1 UNION ALL
SELECT t.N+1 FROM cteTally t WHERE SUBSTRING(#pString,t.N,1) = #pDelimiter
),
cteLen(N1,L1) AS(
SELECT
s.N1,
ISNULL(NULLIF(CHARINDEX(#pDelimiter,#pString,s.N1),0)-s.N1,8000)
FROM cteStart s
)
SELECT
ItemNumber = ROW_NUMBER() OVER(ORDER BY l.N1),
Item = SUBSTRING(#pString, l.N1, l.L1)
FROM cteLen l
;