Database System Concepts
Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
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Chapter 9, Problem 22E

Explanation of Solution

a.

Predicate generated:

The following predicate can be added to queries on takes, to ensure that each faculty member only sees takes tuples corresponding to course sections that they have taught. The predicate assumes that syscontext.user_id() returns the instructor identifier...

Explanation of Solution

b.

SQL Query:

Consider the following query:

select * from takes;

Explanation of Solution

c.

SQL Query:

The following query gives a result tuple that is not in the result of the original query:

select count(*) from takes;

  • The aggregated function above can be any of the aggregate functions, such as sum, average, min or max on any attribute...

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