sql server - Remove ASCII Extended Characters 128 onwards (SQL)

Question

Is there a simple way to remove extended ASCII characters in a varchar(max). I want to remove all ASCII characters from 128 onwards. eg - ù,?,?

I have tried this solution and its not working, I think its because they are still valid ASCII characters?

How do I remove extended ASCII characters from a string in T-SQL?

Thanks

Answer 1

The linked solution is using a loop which is - if possible - something you should avoid.

My solution is completely inlineable, it's easy to create an UDF (or maybe even better: an inline TVF) from this.

The idea: Create a set of running numbers (here it's limited with the count of objects in sys.objects, but there are tons of example how to create a numbers tally on the fly). In the second CTE the strings are splitted to single characters. The final select comes back with the cleaned string.

DECLARE @tbl TABLE(ID INT IDENTITY, EvilString NVARCHAR(100));
INSERT INTO @tbl(EvilString) VALUES('????eeee????'),('?a??b?eeee???c?');

WITH RunningNumbers AS
(
    SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS Nmbr
    FROM sys.objects
)
,SingleChars AS
(
    SELECT tbl.ID,rn.Nmbr,SUBSTRING(tbl.EvilString,rn.Nmbr,1) AS Chr
    FROM @tbl AS tbl
    CROSS APPLY (SELECT TOP(LEN(tbl.EvilString)) Nmbr FROM RunningNumbers) AS rn 
)
SELECT ID,EvilString
      ,(
        SELECT '' + Chr 
        FROM SingleChars AS sc
        WHERE sc.ID=tbl.ID AND ASCII(Chr)<128
        ORDER BY sc.Nmbr
        FOR XML PATH('')
      ) AS GoodString
FROM @tbl As tbl

The result

1   ????eeee????    eeee
2   ?a??b?eeee???c? abeeeec

Here is another answer from me where this approach is used to replace all special characters with secure characters to get plain latin