Data Modeling (Relational Database, Code, Graph, Text)

A data model in software engineering is a graph that try to represent the reality and describes how data are represented and accessed.

A Data model graph formally define:

• data entity (node, vertice)
• and relationships among them (egde)

There is two world view:

• a process-oriented
• and an event-oriented

There is not a right or wrong way of doing things as:

• design decision involves trade-offs between:
  • performance
  • against reduction of data duplicate and design complexity.
• every data model is meant to evolve. See Gay marriage: the database engineering perspective

In a RDBMS,

• a table represents a data entity
• and the foreign keys, the relationship

In code,

• a object (of classes) can represent a data entity
• and the relationship (called dependency) are represented by a external variables

See also: Natural Language - Text Modeling

• Data Modeling - Entity (Object, Table)
• Relation - Column
• Data Modeling - Identifier - (Id|Primary|Natural|Surrogate|Business) key
• Data Modeling - Relationships
• Data Modeling - Database Normalization
• Data Modeling - Denormalization
  • Data Modeling - Denormalization Methods (Changing the Database Design to Reduce the Number of Joins)
• Data Modeling - Referential Integrity (cascade)
• Data Modeling - Cardinality
• Data Modeling - Degree of a relationship
• Data Modeling - Data dictionary
• Data Modeling - (Metadata|Descriptor)
• Data Modeling - Ontology

The difference between model (ER, Dimensional, Vault) has everything to do with terminology and method.

There are two basic types of physical models :

• Data Modeling - Entity-Relationship (E-R) (E-R) and

E-R models are designed to minimize data storage redundancy and optimize data updates.

• Dimensional Modeling - Dimensional Schemas

Dimensional models are designed to enhance understandability and to optimize query performance.

• Data Vault

The Data Vault consists of three primary entity types:

• Hubs,
• Links,
• and Satellites.

The Hubs are core business keys, the Links form all relationships, and the Satellites provide all descriptive information.

• Data_model