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MongoDB : sorting documents by multiple fields

To sort documents by multiple fields in the MongoDB shell, use the sort() method after your find() query. The sort() method accepts a document where keys are the field names and values are either 1 for ascending order or -1 for descending order. The order of fields within the sort() document determines the sorting priority.
Here's an example:
Assume a collection named students with documents like:
Code
{ "name": "Alice", "grade": "A", "age": 18 }
{ "name": "Bob", "grade": "B", "age": 19 }
{ "name": "Charlie", "grade": "A", "age": 17 }
{ "name": "David", "grade": "B", "age": 18 }
To sort these documents first by grade in ascending order, and then by age in descending order for students with the same grade:
JavaScript
db.students.find().sort({ grade: 1, age: -1 });
Explanation:
  • db.students.find(): This retrieves all documents from the students collection.
  • .sort({ grade: 1, age: -1 }): This applies the sorting criteria.
    • grade: 1: Documents are primarily sorted by the grade field in ascending order (e.g., "A" before "B").
    • age: -1: For documents that have the same grade, they are then sorted by the age field in descending order (e.g., 19 before 18).
Example Output (based on the sample data):
Code
{ "name": "Charlie", "grade": "A", "age": 17 }
{ "name": "Alice", "grade": "A", "age": 18 }
{ "name": "Bob", "grade": "B", "age": 19 }
{ "name": "David", "grade": "B", "age": 18 }
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