makemigrations vs migrate in Django: Key Differences

🐍 Django makemigrations vs migrate – Complete Guide

Django provides two core commands for database management:

• makemigrations – prepares changes
• migrate – applies changes

They look similar, but they perform completely different roles in the database lifecycle.

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📚 Table of Contents

• Overview
• What is makemigrations?
• What is migrate?
• Full Workflow
• Database Mapping (Simple Math Model)
• CLI Examples
• Comparison Table
• Best Practices
• Related Articles

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🧠 Overview

Django separates planning changes and applying changes to the database.

This avoids direct risky changes to the database and ensures version control for schema evolution.

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⚙️ What is makemigrations?

This command detects changes in models.py and creates migration files.

Command

python manage.py makemigrations

What it does internally:

• Scans model changes
• Compares with last migration
• Generates Python migration scripts

Example Output

View CLI Output

Migrations for 'app':
  app/migrations/0002_add_age_field.py
    - Add field age to Student

Important Idea

It does NOT change the database. It only prepares instructions.

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🚀 What is migrate?

This command applies migration files to the database.

Command

python manage.py migrate

What it does internally:

• Reads migration files
• Converts them into SQL
• Executes SQL on database

Example Output

View CLI Output

Applying app.0002_add_age_field... OK

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🔁 Django Migration Workflow

Step-by-step process:

1. Create or modify model
2. Run makemigrations
3. Generate migration file
4. Run migrate
5. Database updated

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📐 Database Mapping (Simple Mathematical Model)

Think of Django migrations as a transformation function:

\[ Database_{new} = f(Database_{old}, Migration) \]

Explanation:

• Database_old = current schema
• Migration = instructions (like rules)
• f() = transformation engine (Django ORM)

👉 In simple words: Migration is a set of rules that transforms your old database into a new structure.

Another way to think:

\[ Schema_{t+1} = Schema_t + \Delta Changes \]

• \( \Delta Changes \) = new fields, tables, deletions

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🖥️ CLI Example Workflow

Step 1: Create model

class Student(models.Model): name = models.CharField(max_length=100)

Step 2: Run makemigrations

python manage.py makemigrations

Step 3: Migration file created

Generated File

0001_initial.py

Step 4: Apply migration

python manage.py migrate

Step 5: Database updated

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⚖️ makemigrations vs migrate

Feature	makemigrations	migrate
Purpose	Create migration files	Apply migrations to DB
Affects DB?	No	Yes
Output	Python migration scripts	SQL execution
Usage stage	Development step	Deployment/runtime step

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💡 Best Practices

• Always run makemigrations after model changes
• Commit migration files in Git
• Run migrate before deploying
• Never edit migration files manually unless necessary

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🎯 Final Summary

makemigrations prepares changes.

migrate applies changes.

Together, they ensure safe and structured database evolution in Django applications.