Syntax
------ 
SET('value1','value2',...) [CHARACTER SET charset_name]
[COLLATE collation_name]
 
Description
----------- 
A set. A string object that can have zero or more values,
each of
which must be chosen from the list of values 'value1',
'value2', ... A
SET column can have a maximum of 64 members. SET values are
represented internally as integers.
 


URL: https://mariadb.com/kb/en/set-data-type/