Databases, SQLAlchemy Models, Migrations, and CRUD Operations
Connect Flask to relational databases and build real data-driven applications with models and schema evolution.
Inside this chapter
- Why Databases Are Central
- Defining a Model
- CRUD Workflow
- Migrations
- Real Example
Series navigation
Study the chapters in order for the clearest path from Flask basics to scalable application design, APIs, security, and production operations. Use the navigation at the bottom to move smoothly through the full tutorial series.
Why Databases Are Central
Most production Flask applications store users, products, tasks, reports, transactions, permissions, and history in databases. Learning Flask without database integration misses a major part of real backend work.
Defining a Model
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(120), nullable=False)
email = db.Column(db.String(255), unique=True, nullable=False)ORM models give Python code a structured way to interact with relational data.
CRUD Workflow
Create, read, update, and delete operations form the backbone of admin tools, content systems, dashboards, and service APIs. Students should understand both ORM-level usage and what SQL is doing underneath.
Migrations
Migrations help teams evolve database schemas safely over time. As models change, migrations keep the database aligned with application expectations in a controlled, reviewable way.
Real Example
A course platform may store user profiles, enrollments, lessons, and billing status. Flask plus SQLAlchemy can support these workflows while keeping data access structured and maintainable.