Defining mimetypes is of no use, if you can’t put transformations on them. Otherwise you could just put a comment on the column. Because entering your own mimetype will cause serious syntax checking issues and validation, this introduces a high-risk false- user-input situation. Instead you have to initialize mimetypes using functions or empty mimetype definitions.
Plus, you have a whole overview of available mimetypes. Who knows all those mimetypes by heart so he/she can enter it at will?
Posted in: PhpMyAdmin