Page 161 - DMGT505_MANAGEMENT_INFORMATION_SYSTEM

Management Information Systems

Notes 4. Database integrity
5. Efficiency dealing with a large database.
The model went out of favour due to the following limitations:
1. Complex implementation

2. Difficult to manage
3. Lacks structural independence
4. Complexity of application programming & use
5. Implementation limitations

6. Lack of standards.

8.3.6 Network Model

General Electric (GE) developed a DBMS called IDS (Integrated Data System) based on the
network data model in 1967. In this model, a relationship is called a set. Each set is composed of
at least two record types: an owner (parent) record & a member (child) record. A set represents
a 1:M relationship between the owner & the member. The following is a visual representation of
a network DBMS. The major advantages of this model are:
1. Conceptual simplicity
2. Handles more relationship styles
3. Data access flexibility

4. Promotes database integrity
5. Data independence
6. Conformance to standards.

The model was discarded owing to the following disadvantages:
1. System complexity
2. Lack of structural independence.

Entity-relationship Model

It is one of the most widely accepted graphical data modelling tools. It represents data as entities
(e.g., customers, accounts, and bank branch) & their relationships (e.g., account 23456 is held by
Reetesh) in a database. A relationship set depositor associates customers with accounts. It
complements the relational model concepts. The database design in the E-R model is usually
converted into the relational model that is used for storage & processing. E-R models are normally
represented in an Entity-Relationship Diagram (ERD). In these diagrams, an entity is represented
by a rectangle; a diamond connected to the related entities defines a relationship. Each entity is
also described by a set of attributes. An attribute describes a particular characteristic of the
entity.
The advantages of the ER model are:
1. Exceptional conceptual simplicity

2. Visual representation

156 LOVELY PROFESSIONAL UNIVERSITY