There are two main types of databases used in modern apps:

Type Stores Data As… Good For Examples
SQL Tables (rows + columns) Structured, related data MySQL, PostgreSQL, SQLite
NoSQL Flexible documents (JSON) Unstructured or changing data MongoDB, Firebase

SQL Databases (Relational)

  • Store data in tables with fixed columns
  • Use a powerful language called SQL
  • Great for apps with relationships (users, orders, products)
  • Have a fixed schema. More on what a schema is later in the lesson

NoSQL Databases (Document-based)

  • Store data in JSON-like documents
  • Structure can vary — no fixed schema
  • Good for rapidly changing or flexible data

Why We’re Using SQL

  • Valuable skill: SQL is widely used in the industry
  • Beyond development: SQL is used in DevOps, security, data analysis, and many other tech roles
  • Industry standard: Most companies use SQL databases
  • Structured thinking: SQL forces you to think about data relationships clearly, which is essential for good API design
  • Powerful queries: SQL lets you filter, sort, and combine data in complex ways that are harder with NoSQL
  • Foundation: Understanding SQL makes learning NoSQL databases easier later
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