Django Query Set - Order By

order_by() method in Django QuerySets is used to sort query results based on one or more fields, either in ascending or descending order. This helps display data sorted by criteria like salary, name, date, etc., directly from the database query.

In this article we will learn all about order_by method of QuesrySets by performing multiple operations over a dataset, for this we need to first create a model

Creating Model: EmployeeDetails

Assuming you have the following model defined in models.py:

from django.db import models

class EmployeeDetails(models.Model):
    EmployeeId = models.AutoField(primary_key=True)
    EmployeeName = models.CharField(max_length=20)
    EmployeeDepartment = models.CharField(max_length=20, blank=True, null=True)
    Country = models.CharField(max_length=20, blank=True, null=True)
    Salary = models.IntegerField(blank=True)
    
    def __str__(self):
        return self.EmployeeName

Make sure you have migrated this model:

python manage.py makemigrations

python manage.py migrate

Add some sample data via the Django admin or shell before testing.

Using order_by() in the Django Shell

Open the Django shell:

python manage.py shell

1. Sort Employees in Ascending Order by Salary

from yourapp.models import EmployeeDetails

# Retrieve all employees ordered by Salary (lowest first)
employees = EmployeeDetails.objects.all().order_by('Salary')
for emp in employees:
    print(emp.EmployeeName, emp.Salary)

This will display employees starting from the lowest salary:

2. Sort Employees by Salary in Descending Order

# Using '-' prefix to sort descending by Salary
employees = EmployeeDetails.objects.all().order_by('-Salary')
for emp in employees:
    print(emp.EmployeeName, emp.Salary)

The '-' before the field name reverses the order, so the highest salaries appear first:

3. Alternative Descending Order Approaches (Not Recommended)

# Approach 1: Reverse the QuerySet after ascending order
employees = EmployeeDetails.objects.all().order_by('Salary').reverse()

# Approach 2: Using Python list slicing (less efficient)
employees = list(EmployeeDetails.objects.all().order_by('Salary'))[::-1]

for emp in employees:
    print(emp.EmployeeName, emp.Salary)

While these work, using '-Salary' in order_by() is faster and preferred:

4. Sort by Multiple Fields

# Order first by Salary ascending, then by EmployeeName ascending
employees = EmployeeDetails.objects.all().order_by('Salary', 'EmployeeName')
for emp in employees:
    print(emp.EmployeeName, emp.Salary)

Employees are sorted by salary, when salaries are equal, they are sorted alphabetically by name:

Unfortunately, in the above example, our database have no entries with same salaries and thats why the output looks like a regular salary based sorted list

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Article Tags :

• Python
• Python Django

Practice Tags :

• python