mongodb 分组查询

  IMongoCollection<BsonDocument> _collect;
                        string mongoDB_Host = ConfigurationManager.AppSettings["MongoDB"].ToString();
                        string mongoDB_DbName = ConfigurationManager.AppSettings["MongoDB_DBNAME"].ToString();
                        MongoDB.Driver.MongoClient mc = new MongoClient(mongoDB_Host);
                        IMongoDatabase _db = mc.GetDatabase(mongoDB_DbName);
                        _collect = _db.GetCollection<BsonDocument>(TableName);
                        BsonDocument dbMatch = new BsonDocument { { "Day", new BsonDocument("$eq", Day) }, { "StartTime", new BsonDocument("$lt", StartTime) } };
                        BsonDocument dbGroup = new BsonDocument { { "_id", "$EmployeeId" }, { "maxStartTime", new BsonDocument("$max", "$StartTime") } };
                        var aggregate = _collect.Aggregate().Match(dbMatch).Group(dbGroup);
                        List<BsonDocument> list222 = aggregate.ToList<BsonDocument>();
                        if (list222 != null && list222.Count > 0)
                        {
                            // NLogger.Error("分组总和：--   " + list222.Count);
                            foreach (var itt in list222)
                            {
                                gUserLocation g = new gUserLocation();
                                g.EmployeeId = Convert.ToInt32(itt["_id"].ToString());
                                g.StartTime = Convert.ToInt64(itt["maxStartTime"].ToString());
                                gUserLocationlist.Add(g);

                            }

                        }

　　参考：

http://www.cnblogs.com/shaosks/p/5816932.html

http://www.cnblogs.com/lizeyan/p/5411708.html

http://blog.csdn.net/shiyaru1314/article/details/52442957