@hrachcz: #anketa. model: author 1:n books m:n tags. zajima me sql, ktere vybere autory, kteri nenapsali zadnou knihu o PHP (tj. bez tagu PHP).

solution.sql

select *
from authors
where not exists (
	select *
	from books
		left join books_x_tags on (books_x_tags.book_id = books.id)
		left join tags on (tags.id = books_x_tags.tag_id)
	where
		books.author_id = authors.id
		and tags.name = 'PHP'
)

@milo no jasny :) 👍