If you created your site in with a specific collation language and need to change it you can use this great tool to change all the fields:
Unzip the zip file and copy the folder ‘tool_phoca_changing_collation’ into your server (localhost) root. Run the index.php script included in the ‘Collation’ folder. Add the following information into the form:
* Database hostname (e.g. localhost)
* Database username
* Database password
* Database name
* Database collation (add here the collation you want to have for the database, all tables and all columns in all tables.
Please, run this script only if you know what you do. If you have an extensive database, you must change the script execution time in your php settings, because 30 seconds to execute this script can be not enough.