Introduction to MySQL

Introduction

Almost every dynamic website you have ever used — a store, a forum, a social network, a blogging platform — needs somewhere to permanently store its data. Users, products, orders, comments, and posts all have to live somewhere between one visit and the next. That "somewhere" is almost always a database, and for PHP developers, the most common choice by far is MySQL.

Before you connect PHP to a database in the next lesson, this lesson introduces MySQL on its own terms: what it is, how it organizes data, and the basic SQL vocabulary you need to read and write queries.

What is MySQL?

MySQL is a relational database management system (RDBMS) — software that stores data in structured tables and lets you query, insert, update, and delete that data using a language called SQL (Structured Query Language). It is free, open source, extremely fast for typical web workloads, and has been the default database choice for PHP developers for over two decades.

A "relational" database organizes data into separate tables that can be linked ("related") to one another. For example, a `students` table might relate to a `grades` table through a shared student ID, rather than cramming everything into one giant table.

Why PHP and MySQL Go Together

PHP was designed from the beginning with strong, built-in support for talking to databases, and MySQL was one of the very first it supported well. Together they became the backbone of the "LAMP stack" (Linux, Apache, MySQL, PHP) that powered a huge share of the early web — and still powers platforms like WordPress today.

The pairing works so well because both are free, both are easy to install locally (for example, through XAMPP), and PHP has multiple built-in extensions — MySQLi and PDO, which you will meet in upcoming lessons — dedicated specifically to communicating with MySQL.

Tables, Rows & Columns

A MySQL database is made up of one or more tables. Each table has a fixed set of columns (also called fields) that define what kind of data it stores, and any number of rows (also called records), where each row is a single entry.

In the table above, `students` is the table name, `id`, `name`, `age`, and `course` are the columns, and each numbered row is one student record. The `id` column is typically the primary key — a unique value that identifies each row unambiguously.

Creating a Table

Tables are created with the CREATE TABLE statement, where you list each column name alongside its data type.

CREATE TABLE students (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    age INT NOT NULL,
    course VARCHAR(100)
);

Basic SQL Commands

Once a table exists, you use four core SQL commands to work with its data. Together they are often remembered by the acronym CRUD — Create, Read, Update, Delete — which you will explore in depth in an upcoming lesson.

INSERT adds a new row to a table.

INSERT INTO students (name, age, course)
VALUES ('Amit Verma', 21, 'PHP Development');

SELECT reads rows from a table. You can select every column with *, specific columns by name, and filter rows with a WHERE clause.

SELECT * FROM students;

SELECT name, course FROM students
WHERE age > 20;

UPDATE changes existing rows. Always include a WHERE clause — an UPDATE without one changes every row in the table.

UPDATE students
SET course = 'Advanced PHP'
WHERE id = 1;

DELETE removes rows. Just like UPDATE, forgetting the WHERE clause deletes every row in the table.

DELETE FROM students
WHERE id = 3;

Managing MySQL with phpMyAdmin

Typing every SQL command by hand is not the only option. phpMyAdmin is a free, web-based graphical tool for managing MySQL databases, and it comes bundled with XAMPP (the local development environment you likely installed in an earlier lesson).

With phpMyAdmin, you can create databases and tables, browse and edit rows through a spreadsheet-like interface, run raw SQL queries, import and export data, and manage user permissions — all from your browser, without writing a single line of PHP.

Common Mistakes

Best Practices

Frequently Asked Questions

Key Takeaways

Summary

MySQL gives your PHP applications a place to permanently store structured data, organized into tables of rows and columns and manipulated through SQL commands.

In this lesson, you learned what MySQL is, how relational data is organized, the essential SQL commands, and how phpMyAdmin lets you manage a database visually. Next, you will connect PHP directly to MySQL using the MySQLi extension.