T-SQL strip all non-alpha and non-numeric characters

Question

Is there a smarter way to remove all special characters rather than having a series of about 15 nested replace statements?

The following works, but only handles thr

Answer 1

Create a function:

CREATE FUNCTION dbo.StripNonAlphaNumerics
(
  @s VARCHAR(255)
)
RETURNS VARCHAR(255)
AS
BEGIN
  DECLARE @p INT = 1, @n VARCHAR(255) = '';
  WHILE @p <= LEN(@s)
  BEGIN
    IF SUBSTRING(@s, @p, 1) LIKE '[A-Za-z0-9]'
    BEGIN
      SET @n += SUBSTRING(@s, @p, 1);
    END 
    SET @p += 1;
  END
  RETURN(@n);
END
GO

Then:

SELECT Result = dbo.StripNonAlphaNumerics
('My Customer''s dog & #1 friend are dope, yo!');

Results:

Result
------
MyCustomersdog1friendaredopeyo

To make it more flexible, you could pass in the pattern you want to allow:

CREATE FUNCTION dbo.StripNonAlphaNumerics
(
  @s VARCHAR(255),
  @pattern VARCHAR(255)
)
RETURNS VARCHAR(255)
AS
BEGIN
  DECLARE @p INT = 1, @n VARCHAR(255) = '';
  WHILE @p <= LEN(@s)
  BEGIN
    IF SUBSTRING(@s, @p, 1) LIKE @pattern
    BEGIN
      SET @n += SUBSTRING(@s, @p, 1);
    END 
    SET @p += 1;
  END
  RETURN(@n);
END
GO

Then:

SELECT r = dbo.StripNonAlphaNumerics
('Bob''s dog & #1 friend are dope, yo!', '[A-Za-z0-9]');

Results:

r
------
Bobsdog1friendaredopeyo