Chapter 4

Question 1

What is a strong entity?

Answer 1

When you delete a record in one table will illuminate the record in the other table. For example, remove a record in “employee” table will affect the record in the “dependent” table.

Question 2

What is a weak entity?

Answer 2

When deleting a record in the “dependent” table will not affect the “employee” table.

Question 3

What is an Existence dependence?

Answer 3

Entity exists in the database only when it is associated with another related entity occurrence

Question 4

What is an Existence INdependence?

Answer 4

Entity exists apart from all of its related entities

Referred to as a strong entity or regular entity

Question 5

What is Required attribute?

Answer 5

Must have a value, cannot be left empty

Question 6

What are the characters of Optional attribute?

Answer 6

Does not require a value, can be left empty

Question 7

What are the characters of Domain?

Answer 7

Set of possible values for a given attribute

Question 8

What are the characters of Identifiers (Primary Keys)?

Answer 8

One or more attributes that uniquely identify each entity instance

Question 9

What is a Simple attribute?

Answer 9

A derived attribute is an attribute or property in a table that has been calculated or derived using other attributes in the database.

Question 10

What is a Composite attribute?

Answer 10

Attribute that can be subdivided to yield additional attributes

Question 11

What is a Single-valued attribute?

Answer 11

Attribute that has only a single value

Question 12

What are Multivalued attributes?

Answer 12

Attributes that have many values and require creating: Several new attributes, one for each component of the original multivalued attribute

Question 13

What is a Derived attribute?

Answer 13

Attribute whose value is calculated from other attributes: Derived using an algorithm

Question 14

What are Participants?

Answer 14

Entities that participate in a relationship

Question 15

What is Connectivity?

Answer 15

Describes the relationship classification

Question 16

What is Cardinality?

Answer 16

Expresses the minimum and maximum number of entity occurrences associated with one occurrence of related entity. The inner side is always the maximum and the outer side is always the minimum. Have to identify the limit (maximum/minimum).

Question 17

What is a weak relationship?

Answer 17

Primary key of the related entity does not contain a primary key component of the parent entity

Question 18

What is a strong relationship?

Answer 18

Primary key of the related entity contains a primary key component of the parent entity

Question 19

What is Optional participation?

Answer 19

One entity occurrence does not require a corresponding entity occurrence in a particular relationship

Question 20

What is Mandatory participation?

Answer 20

One entity occurrence requires a corresponding entity occurrence in a particular relationship

Question 21

What is Relationship Degree?

Answer 21

Indicates the number of entities or participants associated with a relationship

Question 22

What is Unary relationship?

Answer 22

Association is maintained within a single entity

Question 23

What is Binary relationship?

Answer 23

Two entities are associated

Question 24

What is Ternary relationship?

Answer 24

Three entities are associated