AVG Function in MongoDB

In MongoDB, you can calculate the average using the aggregation framework. You typically use the $group stage to group documents by some criteria and then apply the $avg operator to compute the average value of a specific field within each group.

Here's an example of how to use the aggregation framework to calculate the average in MongoDB:

Suppose you have a collection named sales with documents containing the sales amount for each transaction. You can use the aggregation pipeline to calculate the average sales amount:

db.sales.aggregate([

  {

    $group: {

      _id: null,

      average_sales: { $avg: "$amount" }

    }

  }

])

In this aggregation:

- $group stage groups all documents into a single group (specified by _id: null).

- $avg operator calculates the average value of the amount field within each group.

This aggregation will produce a result with the average sales amount across all transactions. If you have the following documents in the sales collection:

json

{ "_id": 1, "amount": 100 }

{ "_id": 2, "amount": 200 }

{ "_id": 3, "amount": 300 }

{ "_id": 4, "amount": 400 }

{ "_id": 5, "amount": 500 }

The result of the aggregation would be:

json

{ "_id": null, "average_sales": 300 }

This is because the average of 100, 200, 300, 400, and 500 is 300. Adjust the field name (amount in this example) as needed for your specific data structure.