Explain Network and Relational data models
📘 7. Explain Network and
Relational Data Models
🌐 Network Data Model
📌 Definition:
The Network Data Model is a type of database model
that allows many-to-many relationships between data entities. It
organizes data using records and sets, where records represent objects
and sets represent relationships.
- Developed
by CODASYL (Conference on Data Systems Languages) in the 1960s.
- Visualized
as a graph where:
- Nodes
= entities (records)
- Edges
= relationships (sets)
📎 Key Features:
- Supports
complex relationships through pointers.
- More
flexible than the hierarchical model (which only supports
parent-child).
- Records
are connected using links (pointers) instead of foreign keys.
✅ Example:
Think of a university system:
- A Student
can enroll in multiple Courses
- Each Course
can have multiple Students
The network model can represent this many-to-many
relationship directly using sets.
🔍 Advantages:
- Efficient
for navigational access
- Good
for applications with complex relationships
⚠️ Disadvantages:
- Complex
to design and maintain
- Requires
knowledge of physical database structure
🧮 Relational Data Model
📌 Definition:
The Relational Model, introduced by E. F. Codd in
1970, is based on mathematical logic and set theory. It represents
data using tables (called relations), where each row is a record
(tuple) and each column is an attribute.
- Data
is stored in structured tables
- Tables
can be linked using keys (Primary Key & Foreign Key)
📎 Key Features:
- Each
table has a unique primary key
- Relationships
are defined through foreign keys
- Data
retrieval is done using SQL (Structured Query Language)
✅ Example:
|
StudentID |
Name |
|
101 |
Alice |
|
102 |
Bob |
|
CourseID |
CourseName |
|
C01 |
Math |
|
C02 |
English |
|
StudentID |
|
CourseID |
|
101 |
|
C01 |
|
101 |
|
C02 |
|
102 |
|
C02 |
This structure represents a many-to-many relationship
using foreign keys.
🔍 Advantages:
- Easy
to use and understand
- Data
is independent of how it is stored
- Supports
powerful querying with SQL
⚠️ Disadvantages:
- Can be
slower for large datasets with complex relationships
- Relational
joins can be resource-intensive
What is SAP Landscape?
🔁 Comparison Table:
Network vs Relational Data Model
|
Aspect |
Network Model |
Relational Model |
|
Structure |
Graph with records and links (pointers) |
Tables (relations) |
|
Data Representation |
Records and sets |
Rows (tuples) and columns (attributes) |
|
Relationship Type |
Many-to-many via sets |
Many-to-many using foreign keys |
|
Flexibility |
High, but complex |
Easy to understand and manage |
|
Query Language |
Procedural navigation |
Declarative (SQL) |
|
Learning Curve |
Steep |
Moderate to easy |
|
Performance |
Fast for complex navigations |
Slower for complex joins |
- The Network
Model is useful when performance and relationship complexity
matter more than ease of use.
- The Relational
Model is the most widely used today due to its simplicity,
scalability, and SQL support.
Both models play a vital role in the evolution of database
systems and understanding them helps in grasping the fundamentals of modern
data management.
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Explain Network and Relational data models
In the relational model of a database, all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a relational database.
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The purpose of the relational model is to provide a declarative method for specifying data and queries: users directly state what information the database contains and what information they want from it, and let the database management system software take care of describing data structures for storing the data and retrieval procedures for answering queries.
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