Consider the LIBRARY relational database schema description provided below which is used to keep track of books, borrowers, and book loans. The relations are: • BOOK (BookID, Title, PublisherName) • BOOK_AUTHORS (BookID, AuthorName) • PUBLISHER (Name, Address, Phone) • BOOK_COPIES (BookID, BranchID, NumberOfCopies) • BOOK_LOANS (BookID, BranchID, CardNumber, DateOut, DueDate) • LIBRARY_BRANCH (BranchID, BranchName, Address) • BORROWER (CardNumber, Name, Address, Phone) 1. Consider the schema given above: (a) (5 points) Give a primary key for each relation. Are there any relations for which there is an alternate candidate key that you have not chosen as the primary key? If yes, mention the relations, candidate keys and the reason (if any) for your choice of the primary key. (b) (10 points) State all referential integrity constraints that should hold on these relations.

answer(a) occurs after your prediction;

the benefits of raising bc’s minimum wage to $15 through a

series of pre-announced staged increases far outweigh the likely

costs. claims that such an increase will lead to massive job losses

in low-wage sectors of the economy are not credible.

• an increase to $15 would result in some job losses. however,

the likely impact is less than a 1 per cent reduction in the overall

provincial employment rate, and a 7.6 per cent reduction in the

employment rate for those currently making between $10.25

and $15 per hour.

• the large job loss impacts predicted by some opponents of

minimum wages misrepresent the existing economic research. in

reading and using that research, it is important to recognize that

estimates showing job loss effects of minimum wage increases

apply only to teenagers. estimated effects for young adult and

adult workers range from insignificant to non-existent.

• focusing on teenage workers plays up an inaccurate stereotype

about who earns very low wages in bc and leads to exaggerated

claims about job losses. only 26 per cent of those currently making

between $10.25 and $12 are teenagers, and only 5 per cent

of those making between $12 and $15 are teenagers.