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

## The WHERE clause

The SQL **WHERE** clause is used to specify a condition while fetching the data from a single table. If the given condition is satisfied, then those specific records are returned from the table.

### Syntax

The basic syntax of the `SELECT` statement with the `WHERE` clause is as shown below:

```sql
SELECT column1, column2, ... columnN 

FROM table_name

WHERE [condition];
```

You can specify a condition using the comparison or logical operators like >, <, =, `LIKE`, `NOT`, etc.

### Example #1

Let's consider the CUSTOMERS table again. 

| ID  | NAME| AGE  | ADDRESS  | SALARY |
| --- | --- | --- | --- | --- |
| 1     | Mark  |  32   | Texas | 50000.00 |
| 2    | John   |  25   | NY    | 65000.00  |
| 3    | Emily |   23   | Ohio   | 20000.00 |
| 4    | Bill |   25    | Chicago | 75000.00 |
| 5    | Tom   | 27     | Washington | 35000.00    |
| 6     | Jane    |  22 |  Texas | 45000.00    |


Let's say we want to fetch the `ID`, `Name` and `Salary` fields from the CUSTOMERS table, provided that the salary of the customer is greater than $50,000. 

So when we write our SQL query, will get the following result:

# The WHERE clause

The SQL **WHERE** clause is used to specify a condition while fetching the data from a single table. If the given condition is satisfied, then those specific records are returned from the table.

## Syntax

The basic syntax of the `SELECT` statement with the `WHERE` clause is as shown below:

```sql
SELECT column1, column2, ... columnN 

FROM table_name

WHERE [condition];
```

You can specify a condition using the comparison or logical operators like >, <, =, `LIKE`, `NOT`, etc.

## Example #1

Let's consider the CUSTOMERS table again. 

| ID  | NAME| AGE  | ADDRESS  | SALARY |
| --- | --- | --- | --- | --- |
| 1     | Mark  |  32   | Texas | 50000.00 |
| 2    | John   |  25   | NY    | 65000.00  |
| 3    | Emily |   23   | Ohio   | 20000.00 |
| 4    | Bill |   25    | Chicago | 75000.00 |
| 5    | Tom   | 27     | Washington | 35000.00    |
| 6     | Jane    |  22 |  Texas | 45000.00    |


Let's say we want to fetch the `ID`, `Name` and `Salary` fields from the CUSTOMERS table, provided that the salary of the customer is greater than $50,000. 

So when we write our SQL query, will get the following result:

 In this lesson, we will learn how to use the WHERE clause in SQL to view specific data from table.

Introduction

Fundamental Concepts

Data Modeling

Entity-Relationship Data Model

The Relational Data Model

Functional Dependencies

Normalization

Structured Query Language

Conclusion

The WHERE Clause

The WHERE clause

Syntax