Replace values in a CSV string

Question

I have a list of products in comma separated fashion and since the item list was replaced with new product items, I am trying to modify this CSV list with new product item list.

Answer 1

Thanks for this question - I've just learned something new. The following code is an adaptation of an article written by Rob Volk on exactly this topic. This is a very clever query! I won't copy all of the content down here. I have adapted it to create the results you're looking for in your example.

CREATE TABLE #nums (n INT)
DECLARE @i INT 
SET @i = 1
WHILE @i < 8000 
BEGIN
    INSERT #nums VALUES(@i)
    SET @i = @i + 1
END


CREATE TABLE #tmp (
  id INT IDENTITY(1,1) not null,
  plist VARCHAR(MAX) null
)

INSERT INTO #tmp
VALUES('10,11,15,17,19'),('22,34,44,25'),('5,6,8,9')

CREATE TABLE #tmpprod (
  oldid INT NULL,
  newid INT NULL
)

INSERT INTO #tmpprod VALUES(5, 109),(9, 110),(10, 111),(15, 112),(19, 113),(30, 114),(34, 222),(44, 333)

;WITH cte AS (SELECT ID, NULLIF(SUBSTRING(',' + plist + ',' , n , CHARINDEX(',' , ',' + plist + ',' , n) - n) , '') AS prod
    FROM #nums, #tmp
    WHERE ID <= LEN(',' + plist + ',') AND SUBSTRING(',' + plist + ',' , n - 1, 1) = ',' 
    AND CHARINDEX(',' , ',' + plist + ',' , n) - n > 0)
UPDATE t SET plist = (SELECT CAST(CASE WHEN tp.oldid IS NULL THEN cte.prod ELSE tp.newid END AS VARCHAR) + ',' 
            FROM cte LEFT JOIN #tmpprod tp ON cte.prod = tp.oldid
            WHERE cte.id = t.id FOR XML PATH(''))
FROM #tmp t WHERE id = t.id

UPDATE #tmp SET plist = SUBSTRING(plist, 1, LEN(plist) -1)
WHERE LEN(plist) > 0 AND SUBSTRING(plist, LEN(plist), 1) = ','

SELECT * FROM #tmp
DROP TABLE #tmp
DROP TABLE #tmpprod
DROP TABLE #nums

The #nums table is a table of sequential integers, the length of which must be greater than the longest CSV you have in your table. The first 8 lines of the script create this table and populate it. Then I've copied in your code, followed by the meat of this query - the very clever single-query parser, described in more detail in the article pointed to above. The common table expression (WITH cte...) does the parsing, and the update script recompiles the results into CSV and updates #tmp.