MySQL -- greek letters instead of question marks

I think that a good collation for utf8 Greek character fields on MySQL is ' utf8_unicode_ci ' and charset utf8mb4 if planning accommodating all languages ..

to get rid of question marks ... you may enter the following commands
mysql> SET NAMES 'utf8'; SET CHARACTER SET 'utf8';
before entering data to or querying the Greek DB you did not put together, provided they did use utf8.

If you are still getting question marks all over the place they did use another charset. If you are getting question marks or things that do not make sense every so often, it may be that they have been adding data with different charsets.

MySQL show me Greek Letters instead of Question Marks