looking for SQL query to transfer custom field values into tags

Hello,

at the moment I got several infos in custom fields.
i.e. like this:
(KEY = VALUE)
ACTOR = Brad Pitt
DIRECTOR = peter jackson

To make things easier at the frontend I`d like to move the custom field values into their own tag taxonomy groups. one group for ACTORS one for DIRECTORS.

the problem for me is moving the custom field values from more than 1000 posts to the specific tag group.
can I do this with a sql query?

Thanks for any help.