MongoDB query to get specific month|year (not date)?

You can use aggregate framework along with $month projection operator. Let us first create a collection with documents −

> db.specificMonthDemo.insertOne({"StudentName":"Larry","StudentDateOfBirth":new ISODate('1995-01-12')});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cb9a9ca8f1d1b97daf71819")
}
> db.specificMonthDemo.insertOne({"StudentName":"Chris","StudentDateOfBirth":new ISODate('1999-12-31')});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cb9a9db8f1d1b97daf7181a")
}
> db.specificMonthDemo.insertOne({"StudentName":"David","StudentDateOfBirth":new ISODate('2000-06-01')});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cb9a9ee8f1d1b97daf7181b")
}

Following is the query to display all documents from the collection with the help of find() method −

> db.specificMonthDemo.find().pretty();

This will produce the following output −

{
   "_id" : ObjectId("5cb9a9ca8f1d1b97daf71819"),
   "StudentName" : "Larry",
   "StudentDateOfBirth" : ISODate("1995-01-12T00:00:00Z")
}
{
   "_id" : ObjectId("5cb9a9db8f1d1b97daf7181a"),
   "StudentName" : "Chris",
   "StudentDateOfBirth" : ISODate("1999-12-31T00:00:00Z")
}
{
   "_id" : ObjectId("5cb9a9ee8f1d1b97daf7181b"),
   "StudentName" : "David",
   "StudentDateOfBirth" : ISODate("2000-06-01T00:00:00Z")
}

Following is the query to get specific month|year, not date −

> db.specificMonthDemo.aggregate([ {$project: {StudentName: 1, StudentDateOfBirth:
   {$month: '$StudentDateOfBirth'}}}, {$match: {StudentDateOfBirth: 01}} ]).pretty();

This will produce the following output −

{
   "_id" : ObjectId("5cb9a9ca8f1d1b97daf71819"),
   "StudentName" : "Larry",
   "StudentDateOfBirth" : 1
}