Irrespective of whether you utilize MySQL or Oracle, be sure you have configured your database to use the UTF-8 character set. Failure to do so will result in range of issues when attempting to use Unicode characters in Sakai. Consult your database documentation or a local DBA for instructions on how to set your database up properly.
If you are uncertain as to how your database is currently configured, you can check with a query. Here is a sample query for checking an Oracle instance:
For MySQL, the command to see what encoding your database is currently set to is "show create database sakai", assuming, of course, that your database is named "sakai". e.g.:
Converting a database from one character set to another is a non-trivial operation, particularly if it is a large production database. We recommend strongly that you verify this aspect of the database creation and configuration process before deploying Sakai.