Syntax:
UPPER(str)

Returns the string str with all characters changed to uppercase
according to the current character set mapping. The default is latin1
(cp1252 West European).

MariaDB> SELECT UPPER('Hej');
        -> 'HEJ'

See the description of LOWER() for information that also applies to
UPPER(), such as information about how to perform lettercase conversion
of binary strings (BINARY, VARBINARY, BLOB) for which these functions
are ineffective.

URL: https://mariadb.com/kb/en/upper/

