What are some examples of MongoDB aggregation?

Can you give me some examples of MongoDB aggregation?

Sure! MongoDB aggregation is a powerful framework for data processing. For example, you can use the $group stage to group documents by a specific field and calculate sums or averages.

Can you show me a specific example using the $group stage?

Absolutely! Suppose you have a collection of sales records. You can group by the productId and calculate the total sales like this: { $group: { _id: "$productId", totalSales: { $sum: "$amount" } } }.

What about using the $match stage?

The $match stage filters documents before they enter the pipeline. For instance, to find sales greater than $100, you would use: { $match: { amount: { $gt: 100 } } }.

Can you explain how to combine multiple stages?

Certainly! You can chain multiple stages in an aggregation pipeline. For example: db.sales.aggregate([ { $match: { amount: { $gt: 100 } } }, { $group: { _id: "$productId", totalSales: { $sum: "$amount" } } } ]).