SQL ORACLE - complicated query - sql

Question

I have such tables :
Author(name,surname,id_author)
Author_book(id_author, id_book)
Book_theme(id_book,id_theme)
Theme(id_theme, description)
I need to find for each author theme which was used in his every book which was written by himself and wasn't used in any book where he was co-author. Sorry for my poor english.

Answer 1

I agree with David, it's easier to start off with the basics than continue to add to the query to get the answer your looking for. If I understand the question, your looking for all books where the theme is not part of a book that they co-authored...
select name, Author_book.id_book, Theme.id_theme, description
from Author
join Author_book on (Author.id_author = Author_book.id_author)
join Book_theme on (Author_book.id_book = Book_theme.id_book)
join Theme on (Book_theme.id_theme = Theme.id_theme)
where name = 'Bob'
and Book_theme.id_theme not in(select c.id_theme
from Author_book b
join Book_theme c on (b.id_book = c.id_book)
where
Author_book.id_book = b.id_book
and Author.id_author <> b.id_author)
SQL Fiddle Example

Answer 2

I can understand why you might not know where to begin. I find in such cases that it's best to start small and work your way out using subqueries.
To find the books where a given author is not the sole author:
SELECT id_author, id_book
FROM (
SELECT id_author, id_book, COUNT(*) OVER ( PARTITION BY id_book ) AS author_cnt
FROM author_book
) WHERE author_cnt >= 2;
To get the themes from the above books:
SELECT ab2.id_author, bt.id_theme
FROM (
SELECT id_author, id_book, COUNT(*) OVER ( PARTITION BY id_book ) AS author_cnt
FROM author_book
) ab2, book_theme bt
WHERE ab2.author_cnt >= 2
AND ab2.id_book = bt.id_book;
You can do the same for books where the author is the sole author:
SELECT ab1.id_author, bt.id_theme
FROM (
SELECT id_author, id_book, COUNT(*) OVER ( PARTITION BY id_book ) AS author_cnt
FROM author_book
) ab1, book_theme bt
WHERE ab1.author_cnt = 1
AND ab1.id_book = bt.id_book;
Then you can use MINUS to get the set of themes where the author is the sole author of a book, but not the ones where he is co-author:
SELECT ab1.id_author, bt.id_theme
FROM (
SELECT id_author, id_book, COUNT(*) OVER ( PARTITION BY id_book ) AS author_cnt
FROM author_book
) ab1, book_theme bt
WHERE ab1.author_cnt = 1
AND ab1.id_book = bt.id_book
MINUS
SELECT ab2.id_author, bt.id_theme
FROM (
SELECT id_author, id_book, COUNT(*) OVER ( PARTITION BY id_book ) AS author_cnt
FROM author_book
) ab2, book_theme bt
WHERE ab2.author_cnt >= 2
AND ab2.id_book = bt.id_book;