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Unformatted text preview: b. PUBLISHER: Publisher Code is the primary key; Publisher Name is the alternate key. AUTHOR: Author Num is the primary key. BOOK: BookCode is the primary key. WROTE: BookCode; AuthorNum (a two-field composite key) is the primary key. BRANCH: BranchNum is the primary key; BranchName is the alternate key. COPY: BookCode, BranchNum, CopyNum (a three-field composite key) is the primary key. c. PUBLISHER: 0 AUTHOR: 0 BOOK: 1 WROTE: 2 BRANCH: 0 COPY: 2 d. BOOK: PublsiherCode WROTE: BookCode, AuthorNum COPY: BookCode, BranchNum e. In both the WROTE and COPY relations, both parts of the primary key are also foreign keys. In WROTE it is BookCode and AuthorNum. In COPY it is BookCode and BranchNum. This is because both of these relations represent many-to-many relationships. f. WROTE relation. Primary key: BookCode, AuthorNum. Intersection data: Sequence. COPY relation. Primary key: BookCode, BranchNum and CopyNum. Intersection data: Quality and Price....
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- Spring '14
- Foreign key, primary key, Candidate key