1. Example. FUNCTION.sql

IF EXISTS(SELECT 1 FROM sys.objects WHERE name = 'StripWWWandCom')
    DROP PROC StripWWWandCom
GO
 
CREATE FUNCTION StripWWWandCom(
    @pInput     VARCHAR(250)
)
RETURNS VARCHAR(250)
AS
    BEGIN
        DECLARE @WORK VARCHAR(250)
 
        SET @WORK = @pInput
        SET @WORK = REPLACE(@WORK, 'www.', '')
        SET @WORK = REPLACE(@WORK, '.com', '')
 
        RETURN @WORK
    END
 
DECLARE @vWebSite VARCHAR(MAX)
SET @vWebSite = 'www.google.com'
SELECT dbo.StripWWWandCom(@vWebSite)

/** Output **/
---------------------------------------
google