Author Question: A domain is the set of all data types and ranges of values that ________ may assume. A) Entities ... (Read 63 times)

jayhills49

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A domain is the set of all data types and ranges of values that ________ may assume.
 
  A) Entities
  B) Instances
  C) Attributes
  D) Events

Question 2

Summarize the four steps involved in transforming an E-R diagram into normalized relations and then merging them into one consolidated set of relations.
 
  What will be an ideal response?


ricroger

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Answer to Question 1

C

Answer to Question 2

1. Represent entities. Each entity type in the E-R diagram becomes a relation. The identifier of the entity type becomes the primary key of the relation, and other attributes of the entity type become nonprimary key attributes of the relation. 2. Represent relationships. Each relationship in an E-R diagram must be represented in the relational database design. How we represent a relationship depends on its nature. 3. Normalize the relations. The relations created in steps 1 and 2 may have unnecessary redundancy. So we need to normalize these relations to make them well structured. 4. Merge the relations. So far in database design we have created various relations from both a bottom-up normalization of user views and from transforming one or more E-R diagrams into sets of relations. Across these different sets of relations, there may be redundant relations (two or more relations that describe the same entity type) that must be merged and renormalized to remove the redundancy.



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