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How to sum the value of a key across all documents in a MongoDB collection?
To get sum the value of a key across all documents in a MongoDB collection, you can use aggregate().
To understand the above concept, let us create a collection with the document. The query to create a collection with a document is as follows −
> db.sumOfValueDemo.insertOne({"Name":"Larry","Amount":14.50});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ee7272f684a30fbdfd592")
}
> db.sumOfValueDemo.insertOne({"Name":"Mike","Amount":15.68});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ee7342f684a30fbdfd593")
}
> db.sumOfValueDemo.insertOne({"Name":"Carol","Amount":50.32});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ee7412f684a30fbdfd594")
}
> db.sumOfValueDemo.insertOne({"Name":"David","Amount":120.90});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ee7532f684a30fbdfd595")
}Display all documents from a collection with the help of find() method. The query is as follows −
> db.sumOfValueDemo.find().pretty();
The following is the output −
{
"_id" : ObjectId("5c8ee7272f684a30fbdfd592"),
"Name" : "Larry",
"Amount" : 14.5
}
{
"_id" : ObjectId("5c8ee7342f684a30fbdfd593"),
"Name" : "Mike",
"Amount" : 15.68
}
{
"_id" : ObjectId("5c8ee7412f684a30fbdfd594"),
"Name" : "Carol",
"Amount" : 50.32
}
{
"_id" : ObjectId("5c8ee7532f684a30fbdfd595"),
"Name" : "David",
"Amount" : 120.9
}Here is the query to sum the value of a key across all documents in a MongoDB collection:
> db.sumOfValueDemo.aggregate({
... $group: {
... _id: '',
... "Amount": { $sum: '$Amount' }
... }
... }, {
... $project: {
... _id: 0,
... "TotalAmount": '$Amount'
... }
... });The following is the output:
{ "TotalAmount" : 201.4 }
Updated on: 30-Jul-2019
4K+ Views
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