Data and Info Management Exam 1

PRODUCT yields all possible pairs of rows from two tables, also known as the _____ product.

Cartesian

The entity relationship model uses the associative entity to represent a(n) _____ relationship between two or more entities.

M:N

Which of the following is true of business rules?

They allow the designer to set company policies with regard to data. They allow the designer to develop business processes. Correct! They can serve as a communication tool between the users and designers. They provide a framework for the company's self-actualization.

A _____ key can be described as a minimal superkey, a superkey without any unnecessary attributes.

candidate

____ expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity.

cardinality

A(n) _____ is a restriction placed on the data.

constraint

_____ are important because they help to ensure data integrity.

constraints

The decision to store _____ attributes in database tables depends on the processing requirements and the constraints placed on a particular application.

derived

A relationship is an association between _____.

entities

T/F The external model is the representation of the database as "seen" by the DBMS

false

t/f A weak relationship exists if the primary key of the related entity contains at least one primary key component of the parent entity.

false

t/f In a natural join, the column on which the join was made occurs twice in the new table.

false

t/f The SELECT operator yields a vertical subset of a table.

false

t/f The one-to-many (1:M) relationship is easily implemented in the relational model by putting the foreign key of the "1" side in the table of the "many" side as a primary key.

false

A(n) _____ only returns matched records from the tables that are being joined.

inner join

A(n) _____ join links tables by selecting only the rows with common values in their common attribute(s).

natural

A(n) _____ is the conceptual organization of an entire database as viewed by a database administrator.

schema

An internal _____ refers to a specific representation of an internal model, using the database constructs supported by the chosen database.

schema

A(n) _____ relationship is also known as an identifying relationship.

strong

T/F Each row in the relational table is known as an entity instance or entity occurrence in the ER model.

true

T/F In the context of data models, an entity is a person, place, thing, or event about which data will be collected and stored.

true

T/F M:N relationships are not appropriate in a relational model.

true

t/f A composite identifier is a primary key composed of more than one attribute.

true

t/f A weak entity has a primary key that is partially or totally derived from the parent entity in the relationship.

true

t/f If the attribute (B) is functionally dependent on a composite key (A) but not on any subset of that composite key, the attribute (B) is fully functionally dependent on (A).

true

t/f The DIFFERENCE operator subtracts one table from the other.

true

t/f The DIVIDE operation uses one single-column table (e.g., column "a") as the divisor and one two-column table (e.g., columns "a" and "b") as the dividend.

true

Each row in a relation is called a(n)

tuple

A _____ relationship exists when an association is maintained within a single entity.

unary

A _____ entity has a primary key that is partially or totally derived from the parent entity in the relationship.

weak