Use REGEXP_REPLACE as advanced initcap function?

Question

Hi,
I wan't to convert a string "bygger'n" to "Bygger'n", is it possible to do something like this with regexp_replace?
"bygger'n" is just meant as an example, I want to replace all matching patterns with lowercase letters.
Oracle does not seem to consider lower/upper-functions for the replace of patterns:
SQL> select regexp_replace(initcap('bygger''n'), '(''[[:alnum:]])', lower('\1')) try_lower
  2  ,      regexp_replace(initcap('bygger''n'), '(''[[:alnum:]])', ' \1 ') spaces
  3  from   dual
  4  /
TRY_LOWE SPACES
Bygger'N Bygger 'NRegards
Haavard

Answer 1

If you are on 10g you can do it with a Java Stored Procedure that handles regular expressions with a powerful API. Take a look at the Matcher class.
http://www.regular-expressions.info/java.html
http://www.javaworld.com/javaworld/jw-02-2003/jw-0207-java101.html
create or replace java source named MyInitcap as
import java.util.regex.*;
class MyInitcap {
     public static String firstUpper(String s) {
          return Character.toUpperCase(s.charAt(0))+s.substring(1).toLowerCase();
     public static String initcap(String input) {
          Pattern p = Pattern.compile ("((\\w|')+)");
          Matcher m = p.matcher (input);
          StringBuffer sb = new StringBuffer ();
          while (m.find ())
               m.appendReplacement (sb, firstUpper(m.group()));
          m.appendTail (sb);
          return sb.toString();
create or replace function my_initcap (
          string in varchar2
     )return varchar2
as language java name 'MyInitcap.initcap(java.lang.String) return java.lang.String';
/And then
Processing ...
with t as (select 'FIRSTNAME O''MALLEY' col1
             from dual
            union
           select 'FIRST''NAME  TEH''TE'
             from dual
            union
           select 'FORMAT ME BYGGER''N'
             from dual
            union
           select 'OLD MCDONALD'
             from dual
            union
           select 'EVEN OL''DER MACDONALD'
             from dual
select t.col1 source
     , my_initcap(col1) formatted
  from t
Query finished, retrieving results...
        SOURCE              FORMATTED                                   
EVEN OL'DER MACDONALD Even Ol'der Macdonald  
FIRST'NAME  TEH'TE    First'name  Teh'te    
FIRSTNAME O'MALLEY    Firstname O'malley     
FORMAT ME BYGGER'N    Format Me Bygger'n     
OLD MCDONALD          Old Mcdonald          
5 row(s) retrievedBye Alessandro