How do I update multiple characters at specified positions in a string while avoiding looping?

Question

DECLARE @mytestvar NVARCHAR(MAX) = '2,3,4,5,6'
UPDATE tblMessageState
SET UserFilingCategoryStatus = STUFF(UserFilingCategoryStatus,CONVERT(INT,a.Value),1,'0')
FROM dbo.udtfSplit(@mytestvar, ',') a
WHERE MessageID = 1
This is the farthest I have gotten. This only updated the character in position 2 ...I also want it to update the character in position 3 and 4 etc... or whatever positions I input. Is there some CROSS APPLY trickery I could use ? I really want to avoid looping.
Paul Mauriello

Answer 1

ALTER FUNCTION dbo.fnparseAndreplaceString
@vSplitStr varchar(1000),
@vChangePosStr varchar(100)
RETURNS varchar(100)
AS
BEGIN
Declare @vMyString varchar(100) = @vSplitStr
Declare @vChangeStr varchar(100) = @vChangePosStr
Declare @vResult varchar(100) = ''
Declare @vTable Table (ID int, val nvarchar(100))
;With wcte as (
Select Row_Number()over(Order by name) ID from sys.columns
) --Insert into @vTable
Select @vResult = (Select '' + Case when b.value is Not Null then '1' else Right(SubString(@vMyString,1,ID),1) end
from wcte a
Left Outer Join dbo.fnSplit(@vChangePosStr,',') b on b.value = a.ID
where ID <= Len(@vMyString)
For XML Path(''))
--),1,1,'')
RETURN @vResult
END
GO
Create the function as above and then you can use it in your UPDATE query;
Declare @vMyString varchar(100) = '4567899243'
Declare @vChangeStr varchar(100) = '2,4,8' -- I will replace these positions with 1.
Declare @vTableTest Table (ID int, val varchar(10))
Insert into @vTableTest
Select 1, '123456789' Union All
Select 2, '456783457'
Select *, dbo.fnparseAndreplaceString (val,@vChangeStr) from @vTableTest
Update @vTableTest
Set val = dbo.fnparseAndreplaceString (val,@vChangeStr)
Select * from @vTableTest
Technically you will need two functions in your code. One is above and the other one is dbo.fnSplit. I hope you have the split function that splits the string on the basis of a given character.
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