Q1: What is Data-Manipulation Language (DML)? There are four types of access in DML, explain each one.

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Q2: Assume we have a Library Database consists of the following relations:

author(author_id, first_name, last_name)

author_publication(author_id, publication_id, author_position)

book(book_id, book_title, month, year, editor)

publication(publication_id, title, book_id)

Note: (editor) in books relation refers to (author_id) in authors relation. Some of authors are book editors.

(a) Underline the appropriate primary keys/foreign keys in the above relations.

(b) Write two relational algebra expressions that retrieve:

-The last names of all authors who are book editors only.

-The first name of all authors who are not book editors.

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