? MySQL Introduction

⚡ Quick Overview

MySQL is an open-source relational database management system (RDBMS) based on Structured Query Language (SQL). It is widely used to store and manage data for various applications, from small websites to large-scale enterprise applications.

? Open Source ? Relational ? Scalable ⚡ High Performance ? Secure

? Key Concepts

Database: A collection of related data stored in tables.
Table: Organizes data in rows and columns, similar to a spreadsheet.
Row (Record): A single, complete entry of data in a table.
Column (Field): A specific attribute of the data (such as name or email).
SQL: The language used to interact with the database (create, insert, update, delete, query).

? MySQL Features

Open-Source: MySQL is free to use and available for various platforms.
Relational Database: It organizes data in tables with rows and columns, maintaining relationships between them.
Scalable: MySQL supports large amounts of data and is used by millions of applications worldwide.
High Performance: Known for its fast data retrieval and optimized query performance.
Secure: Supports authentication, access control, and SSL encryption.

? Syntax / Theory

Common SQL statements you will use with MySQL:

CREATE DATABASE – Defines a new database.
USE – Switches to the specified database.
CREATE TABLE – Creates a new table with columns and data types.
INSERT INTO – Adds new records to a table.
SELECT – Retrieves data from one or more tables.

? View Code Example (Basic Operations)

-- Creating a database
CREATE DATABASE my_database;

-- Selecting a database
USE my_database;

-- Creating a table named 'users'
CREATE TABLE users (
  id INT PRIMARY KEY AUTO_INCREMENT,
  name VARCHAR(100),
  email VARCHAR(100)
);

-- Inserting data into the 'users' table
INSERT INTO users (name, email) VALUES ('John Doe', 'john.doe@example.com');

-- Querying all rows from the 'users' table
SELECT * FROM users;

? Example: Company Database

This example demonstrates how to create a simple company database to store employee information.

? View Code Example (Company Database)

-- Creating a database named 'company'
CREATE DATABASE company;

-- Using the 'company' database
USE company;

-- Creating an 'employees' table
CREATE TABLE employees (
  id INT PRIMARY KEY AUTO_INCREMENT,
  name VARCHAR(100),
  position VARCHAR(100),
  salary DECIMAL(10, 2)
);

-- Inserting data into 'employees' table
INSERT INTO employees (name, position, salary)
VALUES ('Alice Johnson', 'Software Engineer', 70000.00);

-- Query to get all employees
SELECT * FROM employees;

? Live Output / Explanation

CREATE DATABASE: Defines a new database (for example, company).
USE: Switches to the specified database so that subsequent commands run in that context.
CREATE TABLE: Defines a new table with specific columns and data types.
INSERT INTO: Adds new records (rows) to a table.
SELECT: Retrieves data from one or more tables, based on the query.

When you run the final SELECT * FROM employees; query in a MySQL client, you will see a result table showing all employees, including the record for Alice Johnson that you inserted.

? Tips & Best Practices

Always back up your database before making changes or updates.
Ensure your table columns are properly indexed for faster data retrieval.
Normalize your database to minimize redundancy and improve data integrity.
Use meaningful names for databases, tables, and columns.
Limit direct access to production databases and use strong authentication.

? Try It Yourself

Try creating your own database and table (for example, a library database with a books table).
Insert multiple records and use different SQL queries to retrieve the data (filter by author, price, etc.).
Experiment with adding constraints like NOT NULL or DEFAULT values on different columns.
Update an existing record using UPDATE and then verify the change with SELECT.
Delete a specific record using DELETE and confirm it is removed.