SQL & PL/SQL

Hi guys,

I watched many threads but I was not able to find an answer to my issue, so I am creating a new one.

I need the convert function to filter a table on a column which contains accented characters. I am using Oracle 10G and my database charset is US7ASCII

This query works fine.
SELECT * FROM User u WHERE UPPER(CONVERT(u.name, 'US7ASCII', 'WE8ISO8859P1')) LIKE UPPER('name%');

But I also need to join this table with a view to get some informations on the user. When I use the convert function on this view, everything is ok :
The object 'code' is my view.
SELECT c.code from city c where convert(c.code, 'US7ASCII', 'WE8ISO8859P1') LIKE 'code';

However, when I try to join these 2 objects, I get an ORA 01482 error : unsupported character set.
SELECT * FROM user u LEFT JOIN city c ON u.code_city = c.code WHERE UPPER(CONVERT(u.name, 'US7ASCII', 'WE8ISO8859P1'))) LIKE UPPER('name%');

I tried to figure out the solution but I really don't understand why this query doesn't work whereas the convert function works fine on the 2 objects.

Thank you for your help