Database Concepts (7th Edition)
7th Edition
ISBN: 9780133544626
Author: David M. Kroenke, David J. Auer
Publisher: PEARSON
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Textbook Question
Chapter 2, Problem 2.21RQ
Explain three possible interpretations of a null value.
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How are nulls defined? Which field is not capable of accepting null values? How come?
Answer the given question with a proper explanation and step-by-step solution.
sid
name
value
working hours
timestamp
14
temperatureΑΒΒ
47
20
11/10/22015 12:00:00
16
humidityBosch
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200
11/11/22015 12:00:00
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temperatureΑΒΒ
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temperatureΑΒΒ
NULL
30
11/12/22015 12:00:00
Write sql statement that calculates the average temperature for the temperature sensor and it will be showed
Write sql statement that will show all the fields of of the table in order not to have duplex values
THE NULLS VALUES MUST BE EXCLUDED .
PLEASE WRITE THE ANSWER IN PAPER
10. Sometimes logic for a query can be quite complex. It is possible to produce the desired
outcomes through the use of subqueries, inline views, and UNION-type statements. For those
methods, the transitional results are not saved in the database but are directly used within the
query. This can lead to achievement issues, particularly when the transitional results have a huge
number of
Explain.
a. columns
b. rows
c. reports
d. databases
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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