ERDs and DFDs

In an ERD, what does a rectangle represent?

• Attribute

• Entity

• Process

• Data flow

Which statement best describes a primary key?

• Can be duplicated

• Uniquely identifies a row

• Always null

• Stores images

The notation 1..N between two entities means:

• One-to-one

• One-to-many

• Many-to-many

• Zero-to-one

In an ERD, a foreign key is:

• The primary key from another entity stored in this table

• A calculated field

• A picture

• The database name

A crow’s-foot (three prongs) at the end of a relationship line indicates:

• Exactly one

• Zero

• Many

• Unknown

An attribute like Age, calculated from DateOfBirth, is called:

• Simple

• Derived

• Composite

• Multivalued

Which diagram is mainly used to model the structure of data in a database?

• DFD

• ERD

• Network diagram

• Gantt chart

Underlining an attribute in an ERD usually shows it is a:

• Optional field

• Foreign key

• Primary key

• Derived field

What is the main purpose of a DFD?

• Show data movement through a system

• Draw employee hierarchy

• Display network packets

• List software code

In a DFD, a process is commonly drawn as a:

• Square

• Circle / rounded rectangle

• Double line

• Arrow