Suggest suitable keys for the relations of the battleships database Classes(class, type, country, numGuns, bore, displacement) Ships(name, class , launched) Battles(name, date) Outcomes(ship, battle , result)

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Write the following referential integrity constraints for the battleships database as in Exercise 7.1.4.( see above) Use your assumptions about keys from that exercise, and handle all violations by setting the referencing attribute value to NULL. a) Every class mentioned in Ships must be mentioned in Classes. b) Every battle mentioned in Outcomes must be mentioned in Battles. c) Every ship mentioned in Outcomes must be mentioned in Ships.

Textbook: Database Systems: The Complete Book 2nd edition, by Hector Garcia-Molina, Jeff Ullman and Jennifer Widom, Prentice Hall, 2008. ISBN: 978-0131873254

http://people.inf.elte.hu/sila/DB1Lect/Ullman_The_Complete_Book.pdf Page 319