T-SQL elimina tutti i caratteri non alfabetici e non numerici

Un modo flessibile;

CREATE FUNCTION [dbo].[fnRemovePatternFromString](@BUFFER VARCHAR(MAX), @PATTERN VARCHAR(128)) RETURNS VARCHAR(MAX) AS
BEGIN
    DECLARE @POS INT = PATINDEX(@PATTERN, @BUFFER)
    WHILE @POS > 0 BEGIN
        SET @BUFFER = STUFF(@BUFFER, @POS, 1, '')
        SET @POS = PATINDEX(@PATTERN, @BUFFER)
    END
    RETURN @BUFFER
END

select dbo.fnRemovePatternFromString('cake & beer $3.99!?c', '%[$&.!?]%')

(No column name)
cake  beer 399c