See slide22onchapter2conceptualdesign page 4 name

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Unformatted text preview: , all three violate 3NF. Page 3 Name Student No 3. {14 marks} Look at the following partially­constructed ER diagram about pet stores, which includes the following: · Merchandise can be of many types, including animals and other types · Animals can be cats, dogs, or other species · Merchandise can be sold, which involves the merchandise, an employee, and a customer · Animals are taken care of by some employee · Animals live in cages a. {6 marks} Make the following changes/additions to the ER diagram: i. Add in the constraint that each animal must be taken care of by some employee ii. Add in the date that an employee takes care of an animal. Note that you should make it possible for an employee to take care of an animal on more than one date iii. Add in the specification that each animal lives in exactly one cage See the above diagram. Note that we could not add an attribute for date to Takes Care of, because each relationship must be uniquely determined by its attributes, so we must add an entity for it. See Slide 22 on Chapter 2: Conceptual design. Page 4 Name Student No b. {6 marks} Transform the ER diagram, including the modifications you made i...
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