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

SELECT MAX(SALARY) AS SECOND_HIGHEST
FROM SALARY   
WHERE SALARY < (SELECT MAX(SALARY) FROM SALARY);

Again, the solution will work without the `SECOND_HIGHEST` alias. 

## Explanation

The nested query in **line 3** will retrieve the highest salary from the table. Then the outer query will retrieve the second highest salary as the WHERE clause will return the salary that is below the maximum salary.    

The slides below will help to visualize the solution:



Again, the solution will work without the `SECOND_HIGHEST` alias. 

# Explanation

The nested query in **line 3** will retrieve the highest salary from the table. Then the outer query will retrieve the second highest salary as the WHERE clause will return the salary that is below the maximum salary.    

The slides below will help to visualize the solution:



Introduction

Fundamental Concepts

Data Modeling

Entity-Relationship Data Model

The Relational Data Model

Functional Dependencies

Normalization

Structured Query Language

Conclusion

Solution to Exercise 4

Solution