Introduction

Why MySQL?

MySQL is the most widely deployed open-source relational database in the world. It powers WordPress (40% of all websites), Wikipedia, GitHub, Facebook, and countless web applications. If you have ever filled out a web form, placed an online order, or logged into a website, there is a good chance MySQL stored the data.

The Relational Model

MySQL organizes data into tables — structured grids of rows and columns. Tables are linked through foreign keys, eliminating data duplication and maintaining consistency. Instead of storing a customer's name on every order, you store a customer id. This is the heart of relational database design.

SQL — One Language for Everything

SQL (Structured Query Language) is a declarative language: you describe what you want, and the database figures out how to retrieve it efficiently. The same SQL you write today will work in MySQL 5.7, MySQL 8.0, MariaDB, and — with minor adjustments — PostgreSQL and SQLite.

What You Will Learn

This course contains 15 lessons across 6 chapters:

  1. Getting Started — The SELECT statement, column aliases, DISTINCT, and filtering with WHERE.
  2. Querying Data — Sorting with ORDER BY, pagination with LIMIT/OFFSET, NULL handling, and string functions.
  3. Table Design — CREATE TABLE, MySQL data types, inserting, updating, and deleting rows.
  4. Joins — INNER JOIN to match rows, LEFT JOIN to include unmatched rows.
  5. Aggregations — COUNT, SUM, AVG, MIN, MAX, GROUP BY, and HAVING.
  6. Advanced Queries — Subqueries, EXISTS, and Common Table Expressions (CTEs).

Each lesson explains a concept with real examples and gives you an exercise to practice against a live database.

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