MongoDb sum query

For example I have the following data in MongoDB:

{ "_id" : ObjectId("524091f99c49c4c3f66b0e46"), "hour" : 10, "incoming", 100}
{ "_id" : ObjectId("5240a045dbeff33c7333aa51"), "hour" : 11, "incoming", 200}
{ "_id" : ObjectId("5240a2ecda0d37f35c618aca"), "hour" : 12, "incoming", 300}

Now I want to query "SUM the number of incoming between 11 - 12" (the result should be 500), how could I do this using Mongo Shell?

As llovet suggested, the aggregation framework is the way to go. Here's what your query would look like:

db.CollectionNameGoesHere.aggregate({ $match: {
	$and: [
		{ hour: { $gte: 11 } },
		{ hour: { $lte: 12 } }
	]
} },
{ $group: { _id : null, sum : { $sum: "$incoming" } } });

You can also shape the resulting document to only contain the sum by adding a $project operator at the end of the pipeline, like so:

{ $project: { _id: 0, sum: 1 } }

Some examples if you use mongoose:

1. Calculate total sum of product prices :

Products.aggregate([ { $match: {} }, { $group:
  { _id : null, sum : { $sum: "$Price" } }
}])
.then(res => console.log(res[0].sum));

( { $match: {} }, can be removed. )

---

2. Sum of Product's prices in each category:

Products.aggregate([{ $group:
  { _id : '$Category', sum : { $sum: "$Price" } }
}])
.then(res => console.log(res));