Extract Numbers Or Letters From Mixed String

Yeah, it's pretty simple. Maybe it'll help someone out.


-- USAGE: fn_extract_chars(string_to_search, 'letters' -or- 'numbers')
CREATE FUNCTION fn_extract_chars (@x varchar(128), @y char(7))
RETURNS varchar(128)
AS
BEGIN
DECLARE @chars varchar(128)
DECLARE @pos int
DECLARE @action varchar(32)
SET @pos = 0
SET @chars = ''

IF @y = 'numbers' SET @action = '[0-9]'
ELSE IF @y = 'letters' SET @action = '[a-zA-Z]'

WHILE @pos < (DATALENGTH(@x) + 1)
BEGIN
IF PATINDEX(@action,SUBSTRING(@x, @pos, 1)) > 0
BEGIN
SET @chars = @chars + (SELECT SUBSTRING(@x, @pos, 1))
END
SET @pos = @pos + 1
END
RETURN(@chars)
END