Consider the following relational schemes for a library database. Book ( Title, Author, Catalog_ no, Publisher, Year, Pr ice ) Collection ( Title, Author, Catalog no )
With in the following functional dependencies:
$${\rm I}.\,\,\,\,\,\,$$ Title Author $$ \to $$ Catalog_no
$${\rm II}.\,\,\,\,$$ Catalog_no $$ \to $$ Title Author Publisher Year
$${\rm III}.\,\,\,\,$$ Publisher Title Year $$ \to $$ Price

Assume { Author, Title } is the key for both schemes. Which of the following statements is true?

Let $$R\left( {A,B,C,D} \right)$$ be a relational schema with the following functional dependencies:
$$A \to B,\,\,B \to C,\,\,C \to D$$ and $$D \to B.$$
The decomposition of $$R$$ into $$(A,B), (B,C)$$ and $$(B,D)$$

Which one of the following statements if FALSE?

Consider the relation enrolled (student, course) in which (student, course ) is the primary key, and the relation Paid (student, amount) where student is the primary key. Assume no null values and no foreign keys or integrity constraints. Assume that amounts $$6000, 7000, 8000,9000$$ and $$10000$$ were each paid by $$20$$% of the students. Consider these query plans (Plan $$1$$ on left, Plan $$2$$ on right) to ''List all courses taken by students who have paid more than $$x''$$.

A disk seek takes $$4ms$$, disk data transfer bandwidth is $$300MB/s$$ and checking a tuple to see if amount is greater than $$x$$ takes $$10\mu s.$$ Which of the following statements is correct?