Database Design Section 5 Quiz

Many to many relationships between entities usually hide what?

Another entity

If a relationship can be moved between instances of the entities it connects, it is said to be:

Transferable

What do you call the entity created when you resolve a M:M relationship?

Intersection entity

If an intersection entity is formed that contains no attributes of its own, its uniqueness may be modeled by

Barring the relationships to the original entities.

Relationships can be Redundant. True or False?

True

Which of the following pairs of entities is most likely to be modeled as a M:M relationship?

TEACHER and SUBJECT AREA (*)

A Diamond on a relationship indicates the Relationship as Non-Tranferable. True or False?

True

What relationship is described by the statements: "Each CUSTOMER may place one or more ORDERs, each ORDER must be placed by one and only one CUSTOMER"

One to Many

Which of the following pairs of entities is most likely to be modeled as a 1:1 relationship?

PERSON and FINGERPRINT (*)

Which of the following is an example of a non-transferable relationship

PERSON to BIRTH PLACE

If the same relationship is represented twice in an Entity Relationship Model, it is said to be

Redundant

If the same relationship is represented twice in an Entity Relationship Model, it is said to be:

Redundant

When you resolve a M:M, you simply re-draw the relationships between the two original entities; no new entities are created. True or False?

False

If two entities have two relationships between them, these relationships can be either _____________ or _____________ .

Redundant or Required (*)

The relationship between CUSTOMER and RECEIPT is an example of a non-transferable relationship. True or False?

True

When you resolve a M:M by creating an intersection entity, this new entity will always inherit:

A relationship to each entity from the original M:M.

A non-transferable relationship means the relationship is mandatory at both sides. True or False?

False

A relationship on an ERD can have attributes. True or False?

False

Every ERD must have at least one non-transferable relationship. True or False?

False

Many to many relationships must be left in the Model. It is important to have them documented as M-M. True or False?

False

Non-transferable relationships can only be mandatory, not optional. True or False?

False

One to many relationships are the most uncommon type of relationships in an ERD. True or False?

False

If a relationship can NOT be moved between instances of the entities it connects, it is said to be:

Non-Transferable

What uncommon relationship is described by the statements: "Each DNA SAMPLE may be taken from one and only one PERSON and each PERSON may provide one and only one DNA SAMPLE"

One to One Optional

A barred relationship on an ERD signifies that the UID of the intersection entity is inherited from the entities that made up the original many to many relationship. True or False?

True

Intersection Entities often have the relationships participating in the UID, so the relationships are often barred. True or False?

True

A non-transferable relationship is represented by which of the following symbols?

Diamond