Aggregate Functions

• Description: Counts the number of items in a collection or those that match a certain condition.
• Example (MongoDB) :

db.collection.count({status: "active"});

Counts the number of documents where the status is “active”.

• Description: Adds together all the numerical values found in a specified field across a collection.
• Example (MongoDB) :

db.sales.aggregate([{$group: {_id: null, totalSales: {$sum: "$amount"}}}]);

Sums up the amount field for all documents in the sales collection.

• Description: Calculates the average of the numerical values in a specified field.
• Example (MongoDB) :

db.sales.aggregate([{$group: {_id: null, averageSale: {$avg: "$amount"}}}]);

Computes the average of the amount field across all documents.

• Description: Returns the maximum value from the specified field.
• Example (MongoDB) :

db.sales.aggregate([{$group: {_id: null, maxSale: {$max: "$amount"}}}]);

Finds the maximum amount in the sales collection.

• Description: Returns the minimum value from the specified field.
• Example (MongoDB) :

db.sales.aggregate([{$group: {_id: null, minSale: {$min: "$amount"}}}]);

Finds the minimum amount in the sales collection.