how to allow accented charaters in oracle using regexp_replace in oracle?

Question

Case: To accept person_name satisfying following criteria:

1. Allows any alphabetic symbols
2. Space
3. Dash
4. Apostrophe
5. Accent grave

Some pre-calculation has been performed to store the name in the string "PERSON_NAME"

LOGIC: SUBSTR(REGEXP_REPLACE(PERSON_NAME,'[^A-Za-z .`''-]+',''),0,50)

SELECT SUBSTR(REGEXP_REPLACE('cafè','[^A-Z|a-z| |.|`|''|-]+'),0,50) 
    FROM dual;

Passing almost all cases except in case of accented characters:

For example:

Expected result: cafè [ie symbol above e ` should not be filtered out]

Actual Result: caf

Answer 1

You can use :

select SUBSTR(REGEXP_REPLACE('cafè-` t *'' {','[[:digit:]]') ,0,50) as "String"
  from dual;

String
--------------
cafè-` t *' {

since there's no information about numeric expressions in your restriction list.