SQL split-string as (key-identity,value) - sql

Question

I've added a function to my DB that splits a comma separated string into separate rows.
Now in my string I have: 1,55,2,56,3,57,etc... where (1) is the rowID and (55) the value I want to enter into row 1 of my table.
How can I modify this function to pull the 1st,3rd,5th,etc... values and 2nd,4th,6th,etc... values into two different columns?
CREATE FUNCTION dbo.SplitStringToValues
(
#List NVARCHAR(MAX),
#Delimiter NVARCHAR(255)
)
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),
E42(N) AS (SELECT 1 FROM E4 a, E2 b),
cteTally(N) AS (SELECT 0 UNION ALL SELECT TOP (DATALENGTH(ISNULL(#List,1)))
ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E42),
cteStart(N1) AS (SELECT t.N+1 FROM cteTally t
WHERE (SUBSTRING(#List,t.N,1) = #Delimiter OR t.N = 0))
SELECT Item = SUBSTRING(#List, s.N1, ISNULL(NULLIF(CHARINDEX(#Delimiter,#List,s.N1),0)-s.N1,8000))
FROM cteStart s;
go
-------------- Update
Thanks everyone for your examples. I'm going to try out each of these until I get something working. I will accept once i figure out which on I can make work.
Thank you,
Alexp

Answer 1

An attempt to help with batch script; please try it out:
DECLARE #List NVARCHAR(MAX) = '1,55,2,56,3,57,10,65,11,88';
DECLARE #Delimiter NVARCHAR(255) = ',';
DECLARE #ListDataTable TABLE
(
ID INT IDENTITY (1, 1)
,DataKey INT
,DataValue INT
)
INSERT INTO #ListDataTable (DataKey, DataValue)
SELECT
value
,LEAD(value, 1, 0) OVER(ORDER BY (SELECT 1))
FROM STRING_SPLIT(#List, #Delimiter) WHERE RTRIM(value) <> '';
-- To get odd key values
SELECT * FROM
(
SELECT DataKey, DataValue FROM #ListDataTable WHERE ID % 2 = 1
) Temp WHERE DataKey % 2 = 1;
-- To get even key values
SELECT * FROM
(
SELECT DataKey, DataValue FROM #ListDataTable WHERE ID % 2 = 1
) Temp WHERE DataKey % 2 = 0;

Answer 2

Modify your function to return two columns: the position and the value. This is easy enough and keeps the function general purpose. Just change the select to:
SELECT Item = SUBSTRING(#List, s.N1, ISNULL(NULLIF(CHARINDEX(#Delimiter, #List, s.N1), 0) - s.N1, 8000)),
ItemNum = row_number() over (order by s.N1)
FROM cteStart s;
Then you can use to get the information you want. Here is one method:
select max(case when ItemNum % 2 = 1 then Item end) as rownum,
max(case when ItemNum % 2 = 0 then Item end) as value
from dbo.SplitStringToValues('1,55,2,56,3,57', ',')
group by (ItemNum - 1) / 2

Answer 3

#Macwise was on to something with LEAD - you could do this:
SELECT rownum = item, value
FROM
(
SELECT itemnumber, item, value = LEAD(item,1) OVER (ORDER BY itemnumber)
FROM dbo.SplitStringToValues('1,44,2,55,3,456,4,123,5,0', ',')
) split
WHERE 1 = itemnumber%2;
Gordon's solution is the best, most elegant pre-2012 solution. Here's another pre-2012 solution that does not require a sort in the execution plan:
SELECT rownum = s1.Item, value = s2.Item
FROM DelimitedSplit8K(#string, ',') s1
INNER MERGE JOIN SplitStringToValues('1,44,2,55,3,456,4,123,5,0', ',') s2
ON 1 = s1.itemNumber % 2 AND s1.ItemNumber = s2.ItemNumber-1;

Answer 4

Instead of changing that function, to get the next row's value next to the id use the LEAD function introduced in SQL SERVER 2012:
SELECT Id, Value
FROM (SELECT
ROW_NUMBER() over (order by(select 1)) as cnt,
t.item AS Id,
Lead(t.item)
OVER (
ORDER BY (SELECT 1)) Value
FROM dbo.Splitstringtovalues('10,20,30,40,50,10,20,30,40,50,60,70', ',')
t)
keyValue
WHERE keyValue.value IS NOT NULL
and cnt % 2 = 1