Data Aggregation using C# and MongoDB

MongoDB can perform aggregation operations, such as grouping by a specified key and evaluating a total or a count for each distinct group.

Use the Group stage to group by a specified key. In the Group stage, specify the group by key in the _id field. Group accesses fields by the field path, which is the field name prefixed by a dollar sign $
  
Follow the Install and Connect to MongoDB step to connect to a running MongoDB instance.

  using System;   
  using System.Threading.Tasks;   
  using MongoDB.Bson;   
  using MongoDB.Driver;   
  namespace MongoDB   
  {   
   class Program   
   {   
    static void Main(string[] args)   
    {   
     DataGrouping(args).Wait();   
     Console.WriteLine("Press Enter");   
     Console.ReadLine();   
    }   
    static async Task DataGrouping(string[] args)   
    {   
     var _connectionString = "mongodb://localhost:27017";   
     var _client = new MongoClient(_connectionString);   
     var _database = _client.GetDatabase("blog");   
     var _collection = _database.GetCollection("users");   
     var _aggregate = _collection.Aggregate().Group(new BsonDocument { { "_id", "$ZipCode" }, { "count", new BsonDocument("$sum", 1) } });   
     var _results = await _aggregate.ToListAsync();   
    }   
   }   
  }