How to strip all non-alphabetic characters from string in SQL Server?

Question

How could you remove all characters that are not alphabetic from a string?

What about non-alphanumeric?

Does this have to be a custom function or are there

Answer 1

this way didn't work for me as i was trying to keep the Arabic letters i tried to replace the regular expression but also it didn't work. i wrote another method to work on ASCII level as it was my only choice and it worked.

 Create function [dbo].[RemoveNonAlphaCharacters] (@s varchar(4000)) returns varchar(4000)
   with schemabinding
begin
   if @s is null
      return null
   declare @s2 varchar(4000)
   set @s2 = ''
   declare @l int
   set @l = len(@s)
   declare @p int
   set @p = 1
   while @p <= @l begin
      declare @c int
      set @c = ascii(substring(@s, @p, 1))
      if @c between 48 and 57 or @c between 65 and 90 or @c between 97 and 122 or @c between 165 and 253 or @c between 32 and 33
         set @s2 = @s2 + char(@c)
      set @p = @p + 1
      end
   if len(@s2) = 0
      return null
   return @s2
   end

GO