6.3.3 The features of different data models and how organisations use them to organise data

Question 1

Define:

Data model

Answer 1

” The logical interrelationships and data flow between different data elements involved in the information world that also documents the way data is stored and retrieved”

Question 2

Fill The Blank:

A data model will help when a database is being designed and will ensure final database is fit for …………… and mean it will be more …………… with all relational tables, ……………… and foreign …….. are fully and complete defined meaning the database’s requirements from the end user will be correctly and fully ………………….. with no missing or ……………………….. data

Answer 2

Purpose, Efficiecnt, Primary, Keys, Represented, Redundant

Question 3

State:

DBMS

Answer 3

Database Management System

Question 4

Explain:

How a hierarchal database model works

Answer 4

Shows the database structure as a tree and tables are only related on a hierarchal basis

Question 5

Fill The Blank:

Hierarchal database model will only generally be used for …………………… of files

Answer 5

Organisation

Question 6

State:

3 advantages of the hierarchal database model

Answer 6

3 of:
* East addition and deletion of data
* Easy to share files based on folders (higher up hierarchy means they get all folders below)
* Supports one-to-many relationships
* Relates to natural hierarchies for organisation

Question 7

State:

3 disadvantages of the hierarchal database model

Answer 7

3 of:
* Hard to share specific sections of data and tracking sharing of data
* Not scalable
* Not flexible
* Difficult to query
* Slow to search
* Prone to anomalies

Question 8

Define:

Conceptual data model

Answer 8

Defines what the system contains, establishing the entities and how they would relate to each other

Question 9

Define:

Logical data model

Answer 9

• Giving the different tables/entities their attributes/columns
• Expands on the conceptual model
• Give primary and foreign keys to each entity

Question 10

Define:

Physical data model

Answer 10

• Describes how the system will be implemented using a specific DBMS
• Includes all datatypes and relationships, with no many-to-many relationships

Question 11

Define:

Relationship model

Answer 11

• Show a database as a collection of relationships
• Shows the relationships between the tables, records and fields using primary and foreign keys

Question 12

Fill The Blank:

An …………… …………………. diagram can be used during creation of the ……………….., logical and ………………… data models

Answer 12

Entity, Relationship, Conceptual, Physical

Question 13

Explain:

The three main parts of an entity relationship diagram (ERD)

Answer 13

• Entities - what will become the tables in a DB
• Columns - are also called attributes which will become fields in a DB
• Relationships - how the entities are linked

Question 14

Fill The Blank:

A completed ERD will not include any many-to-…………. relationships but instead using a link ………..

Answer 14

Many, Entity

Question 15

Define:

Primary Key

Answer 15

A field in a table that allows eaach record to be uniquely identified

Question 16

Define:

Foreign key

Answer 16

Used to link tables together, a field in one table that is linked to a primary key in a different table

Question 17

Define:

Data dictionary

Answer 17

Contain data about the data that will be included in the database (contains metadata)

Question 18

Fill The Blank:

Usually created as part of …………. data modelling and will include each ……….. (table)

Answer 18

Physical, Entity