📌 Introduction

In Django, a model is used to define the structure of data stored in the database.

A model represents a database table, and each attribute in the model represents a column in that table.

In this program, we will:

• create a Student model
• define its fields
• register the app
• apply migrations
• generate the database table

This is the first and most important step in Django database programming.

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🎯 Program Statement

👉 Create a Student model and apply migrations to generate database table.

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🧠 Concept

This program introduces:

• models.py
• model fields
• makemigrations
• migrate

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⚙️ Step 1: Create the App

If the app is not already created, run:

python manage.py startapp myapp

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⚙️ Step 2: Register App in settings.py

📁 File: settings.py

🔹 Path:

myproject/myproject/settings.py

🔹 Code:

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'myapp',
]

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🧠 Explanation

• Django must know that myapp is part of the project
• If the app is not added to INSTALLED_APPS, migrations will not work properly for that app

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⚙️ Step 3: Create Student Model

📁 File: models.py

🔹 Path:

myproject/myapp/models.py

🔹 Code:

from django.db import models

class Student(models.Model):
    name = models.CharField(max_length=100)
    age = models.IntegerField()
    course = models.CharField(max_length=100)
    email = models.EmailField(unique=True)

    def __str__(self):
        return self.name

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🧠 Explanation

We created a model named Student with 4 fields:

• name → stores student name
• age → stores age
• course → stores course name
• email → stores email address

Field Types Used

• CharField → for text values
• IntegerField → for whole numbers
• EmailField → for email addresses

unique=True

This ensures that no two students can have the same email address.

__str__() method

This defines how the object will appear in admin panel and shell output.
Instead of showing Student object (1), Django will display the student’s name.

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⚙️ Step 4: Create Migration File

Run this command:

python manage.py makemigrations

✅ Example Output:

Migrations for 'myapp':
  myapp/migrations/0001_initial.py
    + Create model Student

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🧠 Explanation

• makemigrations checks changes in models.py
• It creates a migration file describing what changes should be made in the database

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⚙️ Step 5: Apply Migration to Database

Run this command:

python manage.py migrate

✅ Example Output:

Applying myapp.0001_initial... OK

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🧠 Explanation

• migrate actually creates the table in the database
• After this command, a Student table is generated

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⚙️ Step 6: Database Table Generated

After migration, Django creates a database table for the model.

If you are using the default SQLite database, the data will be stored in:

📁 File: db.sqlite3

🔹 Path:

myproject/db.sqlite3

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🧠 Table Name Note

By default, Django creates the table name as:

myapp_student

Format:

appname_modelname

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⚙️ Step 7: Optional – Verify in Admin or Database Browser

You can verify that the table was created by:

• opening SQLite database in DB Browser for SQLite
• checking Django admin later
• using Django shell in the next post

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🌐 Output / Result

After running migrations successfully:

• Migration file is created in myapp/migrations/
• Student table is created in database

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🧠 How It Works

1. We define the model in models.py
2. Django reads the model structure
3. makemigrations creates migration instructions
4. migrate applies those instructions to database
5. Database table is generated

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🔥 Key Concepts

Model Class

class Student(models.Model):

A model must inherit from models.Model.

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Character Field

name = models.CharField(max_length=100)

Stores text with maximum length.

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Integer Field

age = models.IntegerField()

Stores numeric integer values.

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Email Field

email = models.EmailField(unique=True)

Stores email and enforces uniqueness.

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Migration Command

python manage.py makemigrations

Creates migration file.

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Apply Command

python manage.py migrate

Creates table in the database.

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⚠️ Common Errors

❌ App not added in INSTALLED_APPS

If myapp is missing in settings.py, Django may not detect the model correctly.

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❌ Forgot to run makemigrations

If you directly run migrate without creating migrations, the model changes may not be applied.

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❌ Migration created but not applied

makemigrations only creates migration files.
You must also run:

python manage.py migrate

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❌ Indentation error in models.py

Python is indentation-sensitive, so class and methods must be aligned properly.

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❌ Missing __str__() method

The model will still work, but object representation in admin will not be user-friendly.

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🧪 Practice Questions

1. Add one more field called city
2. Add a field marks
3. Create another model called Teacher
4. Change course max length from 100 to 50
5. Add phone field with CharField

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🎤 Viva Questions & Answers

1. What is a model in Django?

A model is a Python class that represents a database table. It defines the structure of data stored in the database.

2. What is the purpose of models.py?

models.py is used to define the database schema in Django. Each model class inside it corresponds to a database table.

3. Why does a model inherit from models.Model?

A Django model must inherit from models.Model so that Django can provide database-related functionality such as table creation and querying.

4. What is CharField in Django models?

CharField is used to store text values of limited length. It requires the max_length argument.

5. What is the use of EmailField?

EmailField is used to store email addresses and provides email-specific validation.

6. What does unique=True do?

It ensures that no duplicate values are allowed in that field across records in the table.

7. What is the purpose of __str__() method in a model?

The __str__() method returns a readable string representation of the object. It is useful in admin panel and shell.

8. What is the difference between makemigrations and migrate?

makemigrations creates migration files based on model changes, while migrate applies those changes to the database.

9. What is a migration in Django?

A migration is a file that keeps track of changes made to models and tells Django how to update the database.

10. Why are migrations important?

Migrations keep the database structure synchronized with the models. They allow safe and systematic schema changes.

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👉 Next Post: Insert Records into the Database using Django Shell or Admin Panel
👉 Back to List: Django Programs (60 Questions with Solutions)

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Further Reading

Introduction to Django Framework and its Features

Django Practice Exercise

Examples of Array Functions in PHP

Basic Programs in PHP

Registration Form Using PDO in PHP

Inserting Information from Multiple CheckBox Selection in a Database Table in PHP

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