Is the solution above is corrcr, if yes, could you explain why? \"if you determi

Question

Is the solution above is corrcr, if yes, could you explain why?

"if you determine that it is left join, how do you know that, please?"

Thank you

Please don't use handwriting in answers, because I cannot understand it.

Pubs Database Schema author(author id, first-name, last name author pub author id, pub id, author-position) book(book.id, book-title, mon year, editor) th, pub(pub-id, title, book-id) author id in author.pub is a foreign key referencing author pub-id in author pub is a foreign key referencing pub book-id in pub is a foreign key referencing book e editor in book is a foreign key referencing author(author-id) Primary keys are underlined Pubs Database State r (author pub) (author) author id first name last name author id pub id author-position John McCarthy 2 Dennis Ritchie 2 2 D1 2 Ken Thompson Claude D1 Shannon Alan Turing G Alonzo Church 6 6 Perry White Moshe Vardi Roy Batty

Explanation / Answer

Answer : 6

The above relational algebra expression means, author_id from author table and editor from book table should be equal .The symbol in the relational algebraic expression means general or theta join.

General join of author and book table where author_id = editor gives you 6 tuples.

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