chapter 2 quiz

Question 1

Which of the following is true about a key?

A) It may be non-unique.
B) It may be unique.
C) It can only identify one row.
D) Both It may be unique and It may be non-unique
E) None of these

Answer 1

D) Both It may be unique and It may be non-unique

Question 2

A(n) ________ is one or more columns of a relation that is used to identify a row.

A) key
B) attribute
C) Record
D) database

Answer 2

A) key

Question 3

To be considered a composite key, a key must contain at least two attributes. (T/F)

Answer 3

True

Question 4

A key must be unique.

Answer 4

False

Question 5

If the condition exists such that knowing the value of attribute X determines the value of attribute Y, then attribute Y is functionally dependent on attribute X. (T/F)

Answer 5

True

Question 6

The primary key is used to identify unique rows in a relation. (T/F)

Answer 6

True

Question 7

Ensuring that every value of a foreign key matches the value of the corresponding primary key is an example of a referential integrity constraint. (T/F)

Answer 7

True

Question 8

While the relational model for databases appears to hold much promise, few commercial databases have implemented it. (T/F)

Answer 8

False

Question 9

A primary key is ________.

A) a candidate key
B) used to represent columns in relationships
C) always automatically generated by the DBMS
D) comprised of exactly one attribute
E) not required to be unique

Answer 9

A) a candidate key