Accent and case insensitive collation in Oracle with LIKE

Question

I have found this answer useful: Accent and case insensitive COLLATE equivalent in Oracle, but my question is regarding LIKE searching with a version 9 Oracle db.

I

Answer 1

one method would be to modify your session parameters NLS_SORT and NLS_COMP:

SQL> SELECT Name FROM CollationTestTable WHERE NAME LIKE '%pe%';

NAME
--------------------------------------------------------------------------------
pepe

SQL> alter session set nls_sort=Latin_AI;

Session altered

SQL> alter session set nls_comp=linguistic;

Session altered

SQL> SELECT Name FROM CollationTestTable WHERE NAME LIKE '%pe%';

NAME
--------------------------------------------------------------------------------
pepe
pépé
PEPE

As shown in another SO, you cannot use the LIKE operator with NLSSORT (this is because, NLSSORT returns a string of bytes that will be used for sorting, and LIKE only works with charater strings)

Update: While setting the NLS parameters would be my first choice, you could also use built-in functions to achieve the same result. A couple of examples:

SQL> SELECT Name
  2    FROM CollationTestTable
  3   WHERE upper(convert(NAME, 'US7ASCII'))
  4         LIKE upper(convert('%pe%', 'US7ASCII'));

NAME
--------------------------------------------------------------------------------
pepe
pépé
PEPE

SQL> SELECT Name
  2    FROM CollationTestTable
  3   WHERE upper(translate(NAME, 'àâéèêìîòôùûÿ', 'aaeeeiioouuy'))
  4         LIKE upper(translate('%pe%', 'àâéèêìîòôùûÿ', 'aaeeeiioouuy'));

NAME
-----------------------------------
pepe
pépé
PEPE