Thank you for the swift response.

Excuse my illiteracy, but would I need to set the $_POST['author_id'] in a previous PHP page? Or amend the SQL database?

The table I am trying to access (a list of author's of books) has the primary key author_id; I thought it would be possible to identify the fields of this table via the key, and was using the aforementioned code to call that data, so that it could be edited if neccesary.

Regards.