Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
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Expert Solution & Answer
Chapter 4, Problem 2PE
Explanation of Solution
a.
Query for the given instruction:
select ID, name, count (course_id, sec_id, year, semester) as “Sections taught” from instructor natural left outer join teaches group by ID, name.
Explanation:
- Here, get a list with instructor’s ID, name, and the number of sections that they have taught using an outer join.
- Use the natural outer join between instructor and teaches tables.
- Get the instructor’s ID, name, and the number of sections taught by the instructor by using a group by clause on the ID and name attribute...
Explanation of Solution
b.
Query without using outer join:
Select ID, name, (where count (*) as “Section taught” from teaches T where T.id = I.id) from instructor I.
Explanation:
- Display a list with instructor’s ID, name, and the number of sections that they have taught using a sub-query...
Explanation of Solution
c.
Query for the given instruction:
select course_id, sec_id, ID; decode (name, NULL, ‘-’, name) from (section natural left outer join teaches) natural left outer join instructor where semester = ‘Spring’ and year = 2018.
Explanation:
- Initially perform a natural left outer between section, teaches and instructor table...
Explanation of Solution
d.
Query for the given instruction:
select dept_name, count (ID) from department natural left outer join instructor group by dept_name
Explanation:
- Initially perform a natural left outer join between department and instructor table...
Expert Solution & Answer
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Check out a sample textbook solutionChapter 4 Solutions
Database System Concepts
Ch. 4 - Prob. 1PECh. 4 - Prob. 2PECh. 4 - Prob. 3PECh. 4 - Prob. 4PECh. 4 - Prob. 5PECh. 4 - Prob. 6PECh. 4 - Prob. 7PECh. 4 - Prob. 8PECh. 4 - SQL allows a foreign-key dependency to refer to...Ch. 4 -
Given the relations a(name, address, title) and...
Ch. 4 - Prob. 11PECh. 4 - Prob. 12PECh. 4 - Prob. 13PECh. 4 - Prob. 14ECh. 4 - Prob. 15ECh. 4 - Prob. 16ECh. 4 - Prob. 17ECh. 4 - Prob. 18ECh. 4 - Prob. 19ECh. 4 - Show how to define a view tot_credits (year,...Ch. 4 - Prob. 21ECh. 4 - Prob. 22ECh. 4 - Prob. 23ECh. 4 - Prob. 24ECh. 4 - Prob. 25ECh. 4 - Prob. 26E
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