Database Design Section 5 Study Guide

Many to many relationships between entities usually hide what? -More attributes -Uniqueness -Another relationship -Another entity

-Another entity

If a relationship can be moved between instances of the entities it connects, it is said to be: -Recursive -Committed -Implicit -Transferable

-Transferable

When you resolve a M:M by creating an intersection entity, this new entity will always inherit: -The attributes of both related entities. -The UID's from the entities in the original M:M. -Nothing is inherited from the original entities and relationship. -A relationship to each entity from the original M:M.

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

Relationships can be Redundant. True or False?

True

If an intersection entity is formed that contains no attributes of its own, its uniqueness may be modeled by -Creating new attributes. -Barring the relationships to the original entities. -Placing the UID attributes from the original entities into the intersection entity. -None of the above.

-Barring the relationships to the original entities.

A non-transferable relationship is represented by which of the following symbols? -Diamond -Heart -Triangle -Circle

-Diamond

What do you call the entity created when you resolve a M:M relationship? -M:M entity -Intersection entity -Inclusion entity -Recursive entity

-Intersection entity

If a relationship can NOT be moved between instances of the entities it connects, it is said to be: -Mandatory -Non-Transferable -Optional -Transferable

-Non-Transferable

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 -Many to Many -Many to More -One to One

-One to Many

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 -Many to Many Mandatory -One to Many Mandatory -One to Many Optional

-One to One Optional

Which of the following pairs of entities is most likely to be modeled as a 1:1 relationship? -TEACHER and SUBJECT AREA -TREE and BRANCH -PERSON and FINGERPRINT -CAR and WHEEL

-PERSON and FINGERPRINT

Which of the following is an example of a non-transferable relationship -PERSON to BIRTH PLACE -EMPLOYEE to DEPARTMENT -TEACHER to SCHOOL -STUDENT to COURSE

-PERSON to BIRTH PLACE

If the same relationship is represented twice in an Entity Relationship Model, it is said to be: -Replicated -Redundant -Removable -Resourceful

-Redundant

If two entities have two relationships between them, these relationships can be either _____________ or _____________ -Redundant and Replicated -Resourced and Really Good -Redundant or Required -Replicated or Required

-Redundant or Required

Which of the following pairs of entities is most likely to be modeled as a M:M relationship? -TREE and BRANCH -TEACHER and SUBJECT AREA -CAR and WHEEL -PERSON and FINGERPRINT

-TEACHER and SUBJECT AREA

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

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

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

True

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

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

True