Gain insights into fundamental database concepts, relational databases, and entity-relationship diagrams. Learn about normalization techniques and basics of SQL to enhance database efficiency.

Databases are universal - they underlie the technology you use every day. They're a crucial component of everything from telecommunications systems, banking systems, and video games to just about any other software system that maintains some amount of persistent data.

In this course, you'll learn about the fundamental concepts of databases, why and when they're used, what relational databases are, and entity-relationship diagrams. You will also be exposed to techniques like normalization that help to increase the efficiency of databases. You'll wrap up with a look at the basics of Structured Query Language (SQL). 

After completing this course, you will be able to move onto more advanced courses involving database systems and SQL.

Database Design Fundamentals for Software Engineers

## Key attributes of an entity type

An important constraint on the entities of an
entity type is the **key** or **uniqueness** constraint on attributes. An entity type usually
has one or more attributes whose values are distinct for each individual entity in the
entity set. Such an attribute is called a **key attribute**, and its values can be used to
identify each entity uniquely. For the EMPLOYEE entity type, a typical key attribute is `Ssn` (Social Security number) as each person has a unique social security number. 

In an ER diagram, each key attribute has its name underlined inside the oval, as illustrated in the figure below:

# Key attributes of an entity type

An important constraint on the entities of an
entity type is the **key** or **uniqueness** constraint on attributes. An entity type usually
has one or more attributes whose values are distinct for each individual entity in the
entity set. Such an attribute is called a **key attribute**, and its values can be used to
identify each entity uniquely. For the EMPLOYEE entity type, a typical key attribute is `Ssn` (Social Security number) as each person has a unique social security number. 

In an ER diagram, each key attribute has its name underlined inside the oval, as illustrated in the figure below:

In this lesson, we discuss the basics of keys and how they are represented using ER diagrams.

Introduction

Fundamental Concepts

Data Modeling

Entity-Relationship Data Model

The Relational Data Model

Functional Dependencies

Normalization

Structured Query Language

Conclusion

Keys

Key attributes of an entity type