Database Concepts (7th Edition)
7th Edition
ISBN: 9780133544626
Author: David M. Kroenke, David J. Auer
Publisher: PEARSON
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Chapter 2, Problem 2.12RQ
Explanation of Solution
Unique Composite key:
- If a primary key consists of more than one attribute to uniquely identify a row or column in a relational
database , then it is referred as unique composite key. - The other name of composite key is compound key or concatenated key.
Example of unique composite key:
The example for unique composite key of Employee relation is given below:
- The combination of the “name” and “Address” attributes in Employee relation are composite keys...
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Chapter 2 Solutions
Database Concepts (7th Edition)
Ch. 2 - Prob. 2.1RQCh. 2 - Define the term entity, and give an example of an...Ch. 2 - Prob. 2.3RQCh. 2 - Prob. 2.4RQCh. 2 - Prob. 2.5RQCh. 2 - Prob. 2.6RQCh. 2 - Prob. 2.7RQCh. 2 - Prob. 2.8RQCh. 2 - Prob. 2.9RQCh. 2 - Define the term unique key and give an example.
Ch. 2 - Prob. 2.11RQCh. 2 - Prob. 2.12RQCh. 2 - Prob. 2.13RQCh. 2 - Describe four uses of a primary key.Ch. 2 - Prob. 2.15RQCh. 2 - Prob. 2.16RQCh. 2 - Prob. 2.17RQCh. 2 - Explain the term foreign key, and give an example.Ch. 2 - Prob. 2.19RQCh. 2 - Prob. 2.20RQCh. 2 - Explain three possible interpretations of a null...Ch. 2 - Give an example of a null value (other than one...Ch. 2 - Prob. 2.23RQCh. 2 - Prob. 2.24RQCh. 2 - Prob. 2.25RQCh. 2 - Prob. 2.26RQCh. 2 - Prob. 2.27RQCh. 2 - Define the term primary key in terms of functional...Ch. 2 - Prob. 2.31RQCh. 2 - Examine the data in the Veterinary Office...Ch. 2 - Prob. 2.33RQCh. 2 - Describe a modification problem that occurs when...Ch. 2 - Prob. 2.35RQCh. 2 - Prob. 2.36RQCh. 2 - Prob. 2.37RQCh. 2 - Apply the normalization process to the Veterinary...Ch. 2 - Prob. 2.39ECh. 2 - Prob. 2.40E
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- Describe three scenarios when a surrogate key should replace a relation's primary key.arrow_forwardWhat are three criteria that indicate that a surrogate key for a relation's main key should be created?arrow_forwardWhat are three reasons why the main key of a relation need to be replaced with a surrogate key?arrow_forward
- What are three cases when a surrogate key might be used in place of a relation's main key?arrow_forwardWhat are three signs that a surrogate key should be generated for the primary key of a relation instead of using the main key?arrow_forwardIf you assume that a relation has no duplicate data, how do you know there is always at least one primary key?arrow_forward
- If there are more than one possible candidate keys, provide some instances of relations that have more than one.arrow_forwardHere are three examples of when it makes sense to create a surrogate key in place of the primary key in a relation.arrow_forwardWhat are three reasons why the main key of a relation has to be replaced with a surrogate key?arrow_forward
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