Introduction to Databases

What is a Database?

A database is an organized collection of data stored electronically. Think of it as a super-powered spreadsheet that can handle millions of rows efficiently.

Relational Databases

The most common type is the relational database — data is organized into tables (like sheets in a spreadsheet) with rows (records) and columns (fields). Tables can be related to each other through keys.

What is SQL?

SQL (Structured Query Language, pronounced "sequel" or "S-Q-L") is the standard language for working with relational databases. Every major database system speaks SQL: MySQL, PostgreSQL, SQLite, SQL Server, Oracle.

Creating Your First Table

Key Concepts

• Table — a collection of related data (e.g., students)
• Row — a single record (e.g., one student)
• Column — a field in the record (e.g., name, email)
• Primary Key — a unique identifier for each row (id)
• Foreign Key — a column that references a primary key in another table

Why Use a Database?

• Scale — handle millions of records efficiently
• Querying — ask complex questions with SQL
• Integrity — enforce rules (no duplicate emails, required fields)
• Concurrent access — multiple users/apps can use it simultaneously
• Backup & recovery — protect your data

In the next lesson, we'll learn how to retrieve exactly the data you need with SELECT, WHERE, and more.