T-SQL trim (and other non-alphanumeric characters)

Question

We have some input data that sometimes appears with   characters on the end.

The data comes in from the source system as varchar() and our attempts to cast a

Answer 1

For large datasets I have had better luck with this function that checks the ASCII value. I have added options to keep only alpha, numeric or alphanumeric based on the parameters.

--CleanType 1 - Remove all non alpanumeric
--          2 - Remove only alpha
--          3 - Remove only numeric
CREATE FUNCTION [dbo].[fnCleanString] (
        @InputString    varchar(8000)
    ,   @CleanType      int 
    ,   @LeaveSpaces    bit 
)   RETURNS varchar(8000)
AS 
BEGIN

    -- // Declare variables
    -- ===========================================================
    DECLARE @Length     int
        ,   @CurLength  int = 1
        ,   @ReturnString varchar(8000)=''

    SELECT @Length = len(@InputString)

    -- // Begin looping through each char checking ASCII value
    -- ===========================================================
    WHILE (@CurLength <= (@Length+1))
    BEGIN
        IF  (ASCII(SUBSTRING(@InputString,@CurLength,1)) between 48 and 57      AND @CleanType in (1,3) )
        or  (ASCII(SUBSTRING(@InputString,@CurLength,1))    between 65 and 90   AND @CleanType in (1,2) )
        or  (ASCII(SUBSTRING(@InputString,@CurLength,1))    between 97 and 122  AND @CleanType in (1,2) )
        or  (ASCII(SUBSTRING(@InputString,@CurLength,1))    = 32    AND @LeaveSpaces = 1 )
        BEGIN
            SET @ReturnString = @ReturnString + SUBSTRING(@InputString,@CurLength,1)
        END
        SET @CurLength = @CurLength + 1
    END

    RETURN  @ReturnString
END