Methodology - Logical Database

Design For The Relational ModelSubmitted by:

Sharmeen Qayyum

Sara Manzoor

Syeda Sundus

Logical database design

methodology for the relational

modelStep 2: Build and Validate logical data model

• To translate the conceptual data model into logical data model

• To validate this model to check that it is structurally correct and able to support the required transaction

Objectives

1. Derive relationship for logical data model

2. Validate relation using normalization

3. Validate relations against user transaction

4. Check integrity constraints

5. Review logical data model with user

6. Merge logical data models into global model

7. Check for future growth

Objective:

to create relationship for logical data model to represent the entities, relationships and attributes that have been identifies.

Strong entity types

Weak entity types

One-to-many binary relationship types

One-to-one binary relationship types

One-to-one recursive relationship types

Superclass/subclass relationship types

Many-to-many binary relationship types

Complex relationship types

Multi-valued attributes

Objective:

To validate the relation in logical data model using normalization

Purpose of normalization is:

• To ensure that the set of relations has a minimal and yetsufficient number of attributes necessary to support datarequirements of the enterprise

• Also the relations should have minimal data redundancyto avoid the problems of update anomalies

Objective:

To ensure that the relations in the logical data model support the required transactions.

• To validate the logical data model

• To ensure that the conceptual data model supported therequired transactions

Objective:

To check integrity constraints are represented in the logicaldata model.

• A logical data model that include all important integrityconstraints in a ‘true’ representation of the datarequirements for enterprise.

We consider the following types of integrity constraints

• Required data• Attribute domain constraints• Multiplicity• Entity integrity• Referential integrity• General constraints

Objective

To review the logical data model with the users to ensure that they consider the model to be a true representation of the data requirements of the enterprise.

Objective

To merge local logical data models into a single global data model that represents all user views of a database.

A local logical data model represents one or more but not all user views of a database where as global logical data model represents all user views of a database.

Objective

To determine whether there are any sufficient changes likely in the foreseeable future and to assess whether the logical data model can accommodate these changes.

Thanks for your patience…