chapter5

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Questions and Answers

In the given ER schema, what does the attribute DLOCATION represent?

  • The foreign key of the DEPARTMENT relation
  • The primary key of the DEPARTMENT relation
  • A composite attribute of DEPARTMENT
  • A multivalued attribute LOCATIONS of DEPARTMENT (correct)

What is the primary key of the relation R in the given mapping?

  • DLOCATION
  • {DNUMBER}
  • DNUMBER
  • {DNUMBER, DLOCATION} (correct)

In the mapping of the n-ary relationship type R, where n>2, what should be included as foreign key attributes in the new relation S?

  • The composite attributes of the relations that represent the participating entity types
  • The foreign keys of the relations that represent the participating entity types
  • The primary keys of the relations that represent the participating entity types (correct)
  • The multivalued attributes of the relations that represent the participating entity types

What is the primary key of the relation SUPPLY, which represents the ternary relationship type SUPPLY?

<p>{SNAME, PARTNO, PROJNAME} (C)</p>
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In the mapping of a binary M:N relationship type, what should be created?

<p>A new relation with foreign keys from the participating entity types (B)</p>
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What should be included as attributes in the new relation S, created for mapping an n-ary relationship type R, where n>2?

<p>Any simple attributes of the n-ary relationship type (D)</p>
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In the given ER schema, what does the attribute DNUMBER represent?

<p>A foreign key representing the primary key of DEPARTMENT (A)</p>
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In the mapping of a multivalued attribute, what should be created?

<p>A new relation with a foreign key from the participating entity type (B)</p>
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In the mapping of a binary 1:N relationship type, what should be included in the relation representing the N-side entity type?

<p>A foreign key representing the primary key of the 1-side entity type (A)</p>
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What does the given ER schema represent?

<p>A database schema for tracking ships (B)</p>
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