📚 Introduction to Databases for Full Stack Python Development

🔍 What is a Database?

A database is a structured collection of data. In full stack apps, it stores and retrieves persistent data — like user accounts, blog posts, product info, etc.

🧱 Types of Databases

1. Relational Databases (SQL)

Structure: Tables with rows and columns

Use SQL (Structured Query Language)

Common tools:

PostgreSQL

MySQL

SQLite (lightweight, often used in development)

📌 Best for structured data and relationships between entities.

2. NoSQL Databases

Flexible, non-tabular data (JSON-like, key-value, document)

Examples:

MongoDB (document-based)

Redis (key-value, in-memory)

📌 Best for unstructured data, fast lookups, or flexible schemas.

🧩 How Python Apps Interact with Databases

ORM (Object-Relational Mapping)

Instead of writing raw SQL, you use Python classes and objects.

Popular Python ORMs:

Framework ORM Tool

Flask SQLAlchemy, Flask-SQLAlchemy

Django Django ORM (built-in)

FastAPI SQLModel, Tortoise ORM

🚀 Example: Flask + SQLite (with SQLAlchemy)

bash

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pip install flask flask_sqlalchemy

python

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from flask import Flask

from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)

app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///app.db"

db = SQLAlchemy(app)

# Define a model

class User(db.Model):

    id = db.Column(db.Integer, primary_key=True)

    username = db.Column(db.String(80), nullable=False)

# Create DB tables

with app.app_context():

    db.create_all()

🔄 CRUD Operations (Create, Read, Update, Delete)

These are the core operations you’ll perform on your database.

Operation Example in Python

Create db.session.add(new_user)

Read User.query.all()

Update user.username = "newname"

Delete db.session.delete(user)

🗃️ Choosing the Right Database

Need Suggested Database

Development simplicity SQLite

Large-scale, production PostgreSQL

Flexible, document-based MongoDB

In-memory cache/store Redis

✅ Best Practices

Always validate input before inserting into a database.

Use migrations (e.g., Alembic or Django Migrations) to manage schema changes.

Never expose raw SQL queries directly to users (avoid SQL injection).

For production: Use a managed DB service (e.g., AWS RDS, GCP Cloud SQL).

🧠 Bonus: Full Stack Database Flow

Here’s how data flows in a full stack Python app:

Frontend (React, HTML) sends request →

Backend (Python) receives via API route →

ORM translates Python code to SQL →

Database performs query and returns result →

Backend sends response →

Frontend displays data to user

Want to Go Deeper?

Let me know if you’d like:

A project walkthrough (e.g., To-Do App with DB)

Advanced database patterns (e.g., joins, indexes, normalization)

Guide on using MongoDB with Python (e.g., with PyMongo or ODMs like MongoEngine)

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How to Build a CRUD Application with Django

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Setting Up RESTful APIs with Flask or Django

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