How to write a function with Oracle regexp to test a domaine name?

I would like to w开发者_Go百科rite a PLSQL function that returns true if the domain name I pass is valid.

I should use regular expression, but I don't know how to do this.

declare  
  ignore boolean;  
begin  
  isDomainSyntaxOk('www.laclasse.com'); --> should return true.   
  isDomainSyntaxOk('www.la classe.com'); --> should return false because of the space char.  
end;  

Any ideas ?

My regex skills are weak, so I'm hoping that someone comes along and fixes this:

create or replace
FUNCTION IS_VALID_DOMAIN (p_DOMAIN IN VARCHAR2) RETURN BOOLEAN IS
BEGIN
  RETURN REGEXP_LIKE(p_DOMAIN, '^[a-z0-9][a-z.0-9]*[a-z]$');
end;

Tanks for Adam Hawkes' idea. I 've found some regExp that does what I want. The function should return true in these cases :

• only alphanum chars.
• accept '.' and '-' but not at first char and not at last char.

It's should be like this :

function isSyntaxeDomaineOk(pDomain varchar2) return boolean is
begin
   return regexp_like(pDomain, '^[a-z0-9][-a-z.0-9]*[a-z0-9]$');
end isSyntaxeDomaineOk;

I finally modified my function to deal with the '..' occurence problem :

function isSyntaxeDomaineOk(pStr varchar2, pChar4Space varchar2 default null) return boolean is
begin
    return regexp_like(pStr, '^[a-z0-9][-a-z.0-9]*[a-z0-9]$') 
                              and not regexp_like(pStr, '\.\.');
end isSyntaxeDomaineOk;

HTH.