And I have my first fully formed SQL SELECT statement! :D
SELECT adverts.id AS adverts_id, adverts.table AS adverts_table, adverts.record_id AS adverts_record_id, adverts.filename, websites.id AS websites_id, websites.table AS websites_table, websites.record_id AS websites_record_id, websites.url, categories.id AS categories_id, categories.name AS categories_name, categories.alias, links.id AS links_id, links.name AS links_name, links.category_id, links.description, links.phone_number, links.email
FROM ((categories INNER JOIN links ON categories.[id] = links.[category_id]) INNER JOIN websites ON links.[id] = websites.[record_id]) INNER JOIN adverts ON links.[id] = adverts.[record_id]
WHERE (((adverts.table)="links") AND ((websites.table)="links"));