SQL Long String into Substrings by a length and whitespaces - sql

Question

I Want to make out of a String ("Hello this is a String That is very odd")
Substrings by a defined legth (eg. 8) so that when string gets cut at index 8 but alway at the whitespaces not in a word.
lenth : 11
("Hello this is a String That is very odd") --> ("Hello this"),("is a String"),("That is"),("very odd")
I alredy have an array of the indexes Of the whitespaces but i dont know further.
I appreciate if you would help me

Answer 1

There is no easy solution...
So the simple answer is: Do not use SQL-Server for this issue. It's just the wrong tool.
Nevertheless this can be done (if you have to):
--Some declared table to mock your scenario
DECLARE #tbl TABLE(ID INT IDENTITY, YourString NVARCHAR(1000));
INSERT INTO #tbl VALUES('Hello this is a String That is very odd')
,('blah')
,('And one withaverylongword');
--use this to define the portion's length. 8 will be to little...
DECLARE #portionLenght INT = 12;
-the query
WITH cte AS
(
SELECT t.ID
,A.[key] AS fragmentPosition
,A.[value] AS fragment
FROM #tbl t
CROSS APPLY OPENJSON(CONCAT('["',REPLACE(t.YourString,' ','","'),'"]')) A
)
,recCTE AS
(
SELECT ID,fragmentPosition,fragment
,0 AS growingIndex
,CAST(fragment AS NVARCHAR(MAX)) AS growingString
FROM cte
WHERE fragmentPosition=0
UNION ALL
SELECT cte.ID
,cte.fragmentPosition
,cte.fragment
,recCTE.growingIndex + CASE WHEN B.newLength>#portionLenght THEN 1 ELSE 0 END
,CASE WHEN B.newLength>#portionLenght THEN cte.fragment ELSE CONCAT(recCTE.growingString,N' ',cte.fragment) END
FROM recCTE
INNER JOIN cte ON cte.ID=recCTE.ID AND cte.fragmentPosition=recCTE.fragmentPosition+1
CROSS APPLY(SELECT LEN(CONCAT(recCTE.growingString,N' ',cte.fragment))) B(newLength)
)
,final AS
(
SELECT *
,ROW_NUMBER() OVER(PARTITION BY ID,growingIndex ORDER BY fragmentPosition DESC) lastGrowing
FROM recCTE
)
SELECT * FROM final
WHERE lastGrowing=1
ORDER BY ID,fragmentPosition;
The result (with length=12)
1 Hello this
1 is a String
1 That is very
1 odd
2 blah
3 And one
3 withaverylongword
The idea in short
we use a trick with OPENJSON to transform your string into a json array and split it with a guaranteed sort order.
we use a recursive CTE to run through your fragments.
each iteration will calculate the total length of the former parts together with the new fragment
depending on this calculation the fragment will either be added or a new protion is opened.
the final CTE will add a partitioned ROW_NUMBER() to find the last entry per portion.
And no, you should not use this... :-)