Question

Assuming that no new \(n\)-tuples are added, find a composite key with two fields containing the Professor field for the database in Table 7.

Short answer

The resultant answer is Professor-Course number and Professor-Time.

Step-by-step solution

Given data 

Table 7 is given.

Concept of sets

The concept of set is a very basic one. It is simple; yet, it suffices as the basis on which all abstract notions in mathematics can be built.\(A\)set is determined by its elements. If\(A\)is a set, write\(x \in A\)to say that\(x\)is an element of\(A\).

Simplify the expression

A composite key is a collection of domains that has a unique value for each \(n\)-tuple.

One of the variables in the primary key is Professor.

In table 7, we note that Department is not a primary key, because Zoology is mentioned more than once in the table for the professor Cruz.

In table 7, we note that Course number is a primary key, because the course number in each row of the table is different.

In table 7, we note that Room is not a primary key, because Al00 is mentioned more than once in the table for the professor Cruz.

In table 7, we note that Time is a primary key, because the time in each row of the table is different for different professors.