MySQL Introduction & Data Types

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MySQL is an open-source Relational Database Management System (RDBMS) developed by Oracle, renowned for extreme query speed, reliability, and widespread deployment.

Relational Architecture & Schema Design

A relational database organizes data into rows and columns within strictly defined tables. Each table has a defined schema that enforces data integrity, primary keys, and relationships via foreign keys.

Data is structured according to normalized entity schemas to prevent redundant data duplication.

Creating a Normalized MySQL Table

Try It Yourself »

CREATE DATABASE IF NOT EXISTS codexia_store;
USE codexia_store;

CREATE TABLE Users (
    UserID INT AUTO_INCREMENT PRIMARY KEY,
    Username VARCHAR(50) NOT NULL UNIQUE,
    Email VARCHAR(100) NOT NULL UNIQUE,
    AccountBalance DECIMAL(10, 2) DEFAULT 0.00,
    CreatedAt TIMESTAMP DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB;

Core MySQL Data Types

Choosing optimal data types reduces disk consumption and dramatically speeds up in-memory buffer indexing:

Category	Data Type	Storage Size	Ideal Use Case
Integer	INT / BIGINT	4 / 8 Bytes	Primary keys, quantities, counters
Decimals	DECIMAL(M, D)	Variable	Exact currency & financial amounts (no floating-point drift)
Strings	VARCHAR(N)	Length + 1 Byte	Usernames, emails, addresses up to N chars
Timestamp	TIMESTAMP	4 Bytes	Automatic record creation/update timestamps

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Test Yourself With Exercise

+15 XP

Which MySQL data type should always be used for storing financial currency values to avoid floating-point approximation errors?

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