# Kroenke Ch2 Solutions Essay

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Chapter 3 and 4 and Relational Algebra Chapter 3: 1. Consider the relation (20 points): PERSON_2 (Name, Sibling, Shoe_Size, Hobby) Assume that the following functional dependencies exist: Name  Sibling Name  Shoe_Size Name  Hobby a. Describe deletion, modification, and insertion anomalies for this relation. Consider the following relation: Name Sibling Shoe_Size Hobby Jones Fred E Model boats Jones Fred E Scuba Diving Jones Sally E Model boats Jones Sally E Scuba Diving Jones Frank E Model boats Jones Frank E Scuba Diving Greene Nikki B Embroidery Chau Jonathan C Scuba diving Chau Eileen C Scuba diving Deletion anomaly: If a Name drops a Hobby, one line must be deleted for each Sibling. For example, if…show more content…
Assume that students can have multiple nicknames. a. State any multivalued dependencies. We will assume that Number  Name where name is not unique (i.e., there may be more than one “John Smith”, each with a different student number). Then the multivalued dependencies are: Number  Sibling Number  Nickname Note: We can not assume that Name  Nickname because Name is not unique. For example, one John Smith may have the nickname “Johnny” while another John Smith has the nickname “Joe”. If Name  Nickname then John Smith  (“Johnny”, “Joe”) which means that both nicknames apply to both John Smiths. But this is not the case – each John Smith has only one nickname, and they are not the same. b. State the functional dependencies. We will assume that Number  Name where name is not unique (i.e., there may be more than one “John Smith”, each with a different student number). Then the functional dependencies are: Number  Name Number  Dorm Number  RoomType RoomType  DormCost Note: This assumes that only RoomType  DormCost – that is, the cost of a certain type of dorm room is the same no matter what dorm the student is living in. An alternate assumption would be that (Dorm, RoomType)  DormCost, where the cost of the type of dorm room varies form dorm to dorm. c. Transform this table into two or more tables such that each table is