Appendix C: Designing Databases

Question 1

Database

Answer 1

Maintains information about various types of inventory, transactions, employees, and warehouses

Question 2

Database Management System

Answer 2

Creates, reads, updates, and deletes data in a database while controlling access and security

Question 3

Relational Database Model

Answer 3

A type of database that stores its information in the form of logically related two dimensional tables

Question 4

Data Model

Answer 4

The logical data structures that detail the relationships among data elements using graphics or pictures

Question 5

Entity Relationship Diagram

Answer 5

A technique for documenting the relationships between entities in a database environment

Question 6

Entity

Answer 6

Also called a table, stores information about a person, place, thing, transaction, or event

Question 7

Attribute

Answer 7

Data elements associated with an entity

Question 8

Composite Attribute

Answer 8

Can be divided into smaller sub parts, which represent more basic attributed that have their own meanings

Question 9

Simple Attributes

Answer 9

Attributes that are not divisible into subparts

Question 10

Single Valued Attribute

Answer 10

Means having only a single value of each attribute of an entity at any given time

Question 11

Example of Single Valued Attribute

Answer 11

A Customer entity allows only one telephone number for each customer

Question 12

Multi Valued Attribute

Answer 12

Means having the potential to contain more than one value for an attribute at any given time

Question 13

Derived Attribute

Answer 13

If an attribute can be calculated using the value of another attribute

Question 14

Stored Attribute

Answer 14

The attribute that is used to derive the attribute

Question 15

Null Valued Attribute

Answer 15

Assigned to an attribute when no other value applied or when a value is unknown

Question 16

Chen Model

Answer 16

Uses rectangles to represent entities. Attributes are expressed in ovals

Question 17

One to One Relationship

Answer 17

A relationship between two entities in which an instance of entity A can be related to only one instance or entity B

Question 18

One to Many Relationship

Answer 18

A relationship between two entities when 1 entity can have many relationships with another entity

Question 19

Many to Many Relationship

Answer 19

A relationship between to entities in which an instance of entity A can be related to many instances of entity B

Question 20

Relational Data Model cannot handle many to many relationships

Answer 20

It is limited to one to one and one to many relationships. Many to many relationships need to be replaced with a collection of one to many relationships. Relationships cannot have attributes

Question 21

Composite Entities

Answer 21

Entities that exist to represent the relationship between to other entities

Question 22

Cardinality

Answer 22

Expresses the specific number of entity occurrences associated with one occurrence of the related entity

Question 23

Primary Key

Answer 23

A field that uniquely identifies a given entity in a table

Question 24

Foreign Key

Answer 24

A primary key of one table that appears as an attribute in another file and acts to provide a logical relationship between the two files