From the docs of MySQL:

DATE_FORMAT(date,format)

Formats the date value according to the format string.

The following specifiers may be used in the format string. The ‘%’ character is required before format specifier characters.

Ranges for the month and day specifiers begin with zero due to the fact that MySQL allows the storing of incomplete dates such as '2004-00-00'.

mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00', '%W %M %Y');
        -> 'Saturday October 1997'
mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00', '%H:%i:%s');
        -> '22:23:00'
mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00',

                          '%D %y %a %d %m %b %j');
        -> '4th 97 Sat 04 10 Oct 277'
mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00',
                          '%H %k %I %r %T %S %w');
        -> '22 22 10 10:23:00 PM 22:23:00 00 6'
mysql> SELECT DATE_FORMAT('1999-01-01', '%X %V');
        -> '1998 52'
mysql> SELECT DATE_FORMAT('2006-06-00', '%d');

        -> '00'

This allows you to format your DATETIME or TIMESTAMP fields, but it doesn't seem to honor your locale setting. As a matter of fact, MySQL does not seem to know how to set the locale at all. It can however set on a per table basis the character set to use (latin1, UTF8, ...).

If you really want to have your DATETIME fields in Greek, have a look at DBIx::Class and its inflate/deflate mechanism or the ColumnHandlers method from DBIx::DataModel which can transform your fields in pretty any way you like.