Database Design

---

Database Design (Modeling)
The database workers study basic properties and interrelationships between data objects in a real-world problem (such as Programming Exercise II) that are part of the enterprise to be modeled. The aim is to provide faithful representation of such objects as columns in relational tables.

Data Model
It is a mathematical formalism with a notation for describing data structures and a set of operations used to manipulate and validate that data. Data models are important because this is often hard to change a database layout once it has been defined.

Two Database Design Approaches
There are commonly two approaches for database design:

E-R (Entity-Relationship) Model

It is an approach to data modeling proposed by P. Chen in 1976. It is based on intuitive recognition of certain real-world data classifications. The model divides a database into two logical parts, entities (e.g., “customer” and “product”) and relations (“buys” and “pays for”).

Database Normalization

It is a series of steps followed to obtain a database design that allows for efficient access and storage of data in a relational database.

A relation in a relational database is said to be in normal form if it satisfies certain constraints. Codd’s original work defined three such forms but there are now five generally accepted steps of normalization. The output of the first step is called First Normal Form (1NF), the output of the second step is Second Normal Form (2NF), etc.