This document discusses four main types of data models: relational, entity-relationship, object-based, and semi-structured. The relational model uses tables to represent data and relationships. The entity-relationship model uses entities, attributes, and relationships. The object-based model combines features of relational and object-oriented models. The semi-structured model allows different attributes for items of the same type and represents data as a labeled graph without a predefined schema. Examples and diagrams are provided to illustrate each model type.

1. Data Models
DEANNA MEDINA
NORTHERN ARIZONA UNIVERSITY
CIT311 ANALYSIS, DESIGN, & DATABASES:
DATABASE THEORIES: ASSIGNMENT 1.1
JULY 24, 2017

2. Four Types of Data Models
• Uses a collection of
tables representing
data and relationships
Relational
• Uses a collection of
basic objects, called
entities, and
relationships between
the entities
Entity-
Relationship
• Combines the features
of object-oriented and
relational data models
Object-Based
• Allows for the
specification of data
where separate data
items of the same type
may have different
sets of attributes
Semi-
Structured

3. Relational Data Models
• Data and relationships are represented as tables containing columns
with unique names.
• Based on the concept of mathematical relations
• The logical structure of the data model requires only that the
database be perceived by the user as tables

4. Relational Schema
• branchNo represents the
primary key for the Branch
table
• branchNo is used as a foreign
key in the Staff table to show
the relationship between the
two tables

5. Entity-Relationship Model
• A type of Object-Based Model
• Uses concepts of entities, attributes, and relationships

6. Entity-Relationship Diagram
• Entities are represented as
rectangles
• Actions are represented by
diamonds
• Attributes are represented
by ovals.
• Connecting lines represent
relationships

7. Object Based Model
• Uses the concepts of entities, attributes, and relationships
• Types of Object Based Models
• Entity Relationship
• Object-Oriented
• Semantic
• Functional

8. Object-Based Models
USE RELATIONSHIPS BETWEEN TABLES AVOIDING DUPLICATION
OF INFORMATION IN THE DATABASE

9. Semi-Structured Model
• There is no separation between the data and the schema
• A labled graph is used to represent data
• There is no predefined schema

10. Semi-Structured Model
http://www.dbinfoblog.com/post/126/semistructured-data-representation/
The graph to the left represents a
semi-structured model for the
movie StarWars and the
actors/actresses that play in it.

11. References
Connolly,T.M., & Begg,C.E. (2010). Database Systems: A Practical Approach to Design, Implementation,
and Management (5th ed., pp. 1-14). Upper Saddle River, NJ: Addison-Wesley.
Entity Relationship Diagram. (n.d.) Retrieved July 25, 2017 from https://www.smartdraw.com/entity-
relationship-diagram/