Data Models

Back to: DATA PROCESSING SS 3

 

Welcome to class! 

In today’s class, we will be talking about data models. Enjoy the class!

Data Models

Definition of data models

Data model Is the process of structuring and organizing data.

Types of data models

1. Flat
2. Hierarchical
3. Network
4. Relational
5. Object-Relational
6. Star Schema

Significance of data models

1. A well-developed data model can foster an improved understanding of the organization
2. Data model helps in structuring and organizing of data
3. It imposes constraints or limitations on the data placed within the structure

Standard data model

A standard data model or industry-standard data model is a data model that is widely applied in some industry and shared amongst competitors to some degree. Examples are: ISO 10303, ISO 15926, IDEAS GROUP.

Normalization

It is the process of efficiently organizing data in a database by reducing duplication or redundancy and design flaws.

Normal form

Provide criteria for determining a table’s degree of vulnerability to logical inconsistencies and anomalies.

Classes of normal form

1^st, 2^nd, 3^rd, BNC, 4^th and 5^th normal forms

Determinant of normal form

1. The minimal number of attributes necessary to support the data requirements of the enterprise
2. Attributes with a close logical relationship are found in the same relation
3. Minimal redundancy with each attribute represented only once with the important exception of attributes that form all or part of foreign keys.

Evaluation

1. Define data model
2. State types of data model

Concept of keys

• Primary key:

It is the attribute used to identify a record uniquely in a table or database

• Composite primary key:

Two or more keys used as a primary key

• Foreign key:

It is the field or attribute of a table that matches the primary key of another table.

Entity Relationship Diagram (ERD)

It is the diagram that illustrates the logical structure of a database.

Components of Entity-Relationship

1. Entities
2. Attributes
3. Relationships

• Entity:

It is anything for which data can be written about in a business.

• Attributes:

Are the data elements that have the smallest units of data that can be described in a meaningful manner.

• Relationship:

It is an association among the instances of one or more entity types

• Cardinality:

Defines the relationships between the entities in terms of numbers.

Types of relationship

1. One-to-One
2. One-to-Many
3. Many-to-Many

General evaluation

1. (a) Define data model?     (b) State types of data model
2. (a) State five (5) classes of normal forms   (b) Bring the table below to Second Normal Form

Table purchase

CustomerID	StoreID	Purchase Location
1	1	Lagos
1	3	Kano
2	1	Lagos
3	2	Abuja
4	3	Kano

Hint: This table has a composite primary key [CustomerID, StoreID]

Weekend assignment

1. Data models describe ……… data for storage in data management systems (a) structured (b) unstructured (c) integer (d) alphabetic
2. Which of this is not an example of standard data model (a) ISO 10303 (b) ISO 15926    (c) IDEAS GROUP d) Good shepherd
3. ……….. key is a field in a relational table that matches a primary key of another table (a) foreign (b) surrogate (c) primary (d) candidate

4. ……………. is a graphical representation of entities and their relationships to each other (a) Entity-Relationship Diagram (b) Entity-Relationship Picture (c) Entity-Relationship Data (d) Entity-Relationship Symbol
5. A roof covers a building describes …………relationship (a) one-to-one (b) one-to-many  (c) many-to-many(d) None of the above

Theory

1.      (a) Define the following terms (i) Entity (ii) Attribute  (iii) Relationship

(b) What is cardinality?

(c) Mention and explain three types of relationship in ERD with one example each

2.      (a) Define the following (i) Primary key (ii) Foreign key (iii) Composite primary key

(b) Explain the term Normal Form.

(c) Design a database of your choice indicating the primary key and the foreign key

  

In our next class, we will be talking about Indexes: Definition, Clustered versus Unclustered indexes.  We hope you enjoyed the class.

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