1Z0-006 Entity-Relationship Modeling 2

Question 1

In an ER diagram, which symbol is used to represent a weak entity?

Accepted Answer

Double rectangle

Answer

A weak entity is depicted with a double rectangle to distinguish it from a regular (strong) entity.

Question 2

What is a 'discriminator' (partial key) in the context of weak entities?

Accepted Answer

An attribute that uniquely identifies weak entity instances among those associated with the same owner entity

Answer

A discriminator, or partial key, distinguishes weak entity instances that belong to the same strong (owner) entity.

Question 3

Which relationship type links a weak entity to its owner entity in an ER diagram?

Accepted Answer

Identifying relationship

Answer

An identifying relationship (drawn as a double diamond) connects a weak entity to its owner entity, providing the context needed for identification.

Question 4

A 'derived attribute' in an ER diagram is best described as:

Accepted Answer

An attribute whose value can be calculated from other stored attributes

Answer

Derived attributes, shown with a dashed ellipse, are computed at query time from other attributes rather than stored persistently.

Question 5

In an ER model, which of the following best describes a 'composite attribute'?

Accepted Answer

An attribute composed of several sub-attributes that together form a meaningful whole

Answer

A composite attribute is divided into smaller sub-parts, such as 'Full Name' broken into First Name, Middle Name, and Last Name.

(1Z0-006) Oracle Database Foundations Associate Practice Test