1Z0-006 Entity-Relationship Modeling 5

Question 1

When mapping a many-to-many (M:N) binary relationship to relational tables, the correct approach is to:

Accepted Answer

Create a new junction table with foreign keys referencing both entity tables

Answer

An M:N relationship requires a junction (cross-reference) table whose composite primary key consists of the primary keys of both participating entities.

Question 2

Which of the following best describes 'cardinality ratio' in an ER relationship?

Accepted Answer

The maximum number of relationship instances in which an entity instance can participate

Answer

Cardinality ratio (1:1, 1:N, M:N) specifies the maximum number of relationship instances an entity can participate in on each side.

Question 3

What is the purpose of a 'surrogate key' in a relational table derived from an ER model?

Accepted Answer

To provide a system-generated, artificial primary key when no suitable natural key exists

Answer

A surrogate key is a system-generated identifier (often an auto-incremented integer) used when a natural primary key is unavailable or impractical.

Question 4

In an ER diagram, a multivalued attribute is depicted as:

Accepted Answer

A double ellipse

Answer

A double ellipse represents a multivalued attribute, indicating that an entity instance can have multiple values for that attribute.

Question 5

When a multivalued attribute is converted to a relational schema, the standard practice is to:

Accepted Answer

Create a separate table for the multivalued attribute with a foreign key referencing the original entity

Answer

To maintain 1NF, a multivalued attribute is placed in its own relation (table) that references the owning entity via a foreign key.

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

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

1Z0-006 Entity-Relationship Modeling 5