MongoDB-তে ক্ষেত্র গণনা অনুসারে আমি কীভাবে সংগ্রহ এবং গোষ্ঠীবদ্ধ করতে পারি?

MongoDB aggregate(), $group এবং aggregate collection ব্যবহার করুন। আসুন নথি-

> db.demo616.insertOne({"details":{"Name":"Chris","Age":21}});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e99bfac65492f6c60d00283")
}
> db.demo616.insertOne({"details":{"Name":"Chris","Age":22}});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e99bfb065492f6c60d00284")
}
> db.demo616.insertOne({"details":{"Name":"Bob","Age":23}});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e99bfb865492f6c60d00285")
}
> db.demo616.insertOne({"details":{"Name":"Sam","Age":21}});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e99bfbd65492f6c60d00286")
}
> db.demo616.insertOne({"details":{"Name":"Chris","Age":24}});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e99bfc165492f6c60d00287")
}

Find() পদ্ধতি -

> db.demo616.find();

এটি নিম্নলিখিত আউটপুট −

{ "_id" : ObjectId("5e99bfac65492f6c60d00283"), "details" : { "Name" : "Chris", "Age" : 21 } }
{ "_id" : ObjectId("5e99bfb065492f6c60d00284"), "details" : { "Name" : "Chris", "Age" : 22 } }
{ "_id" : ObjectId("5e99bfb865492f6c60d00285"), "details" : { "Name" : "Bob", "Age" : 23 } }
{ "_id" : ObjectId("5e99bfbd65492f6c60d00286"), "details" : { "Name" : "Sam", "Age" : 21 } }
{ "_id" : ObjectId("5e99bfc165492f6c60d00287"), "details" : { "Name" : "Chris", "Age" : 24 } }

ক্ষেত্র গণনা −

> db.demo616.aggregate(
... [
...    {
...       $group:{_id:"$details.Name",Total:{$sum:1}}}
... ]
... );

এটি নিম্নলিখিত আউটপুট −

{ "_id" : "Sam", "Total" : 1 }
{ "_id" : "Bob", "Total" : 1 }
{ "_id" : "Chris", "Total" : 3 }