C#對MongDB取資料的常用代碼

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1、使用彙總取最新的即時資料（每一個測站有多條資料，取日期最新的資料。也就是每個測站取最新的值）

var group = new BsonDocument {                {"_id",new BsonDocument                {                    {"stationID","$stationID"},                    {"stationName","$stationName" }                }        },                //{"stationID",new BsonDocument{ { "stationID", "$stationID" } } },                {"stationID",new BsonDocument("$last","$stationID")},                { "TimeData",new BsonDocument("$max","$TimeData")},                {"eValue" ,new BsonDocument("$last","$eValue")}            };

var collection = MoDataBase.GetCollection<BsonDocument>(tablename);

 var list = collection.Aggregate().Group(group).ToListAsync().Result;            double value = 0.0;            foreach (BsonDocument bsondoc in list)            {                double evalue = double.TryParse(bsondoc.GetElement("eValue").Value.ToString(), out value) ? value : 0;                string stationid = bsondoc.GetElement("stationID").Value.ToString();

2、普通的按照排序取最新的資料

如果一個測站一個表名

/// <summary>        /// 擷取資料庫中每條資料對應的時間放到圖表的橫座標上        /// </summary>        /// <param name="StatioID">監測站ID</param>        /// <param name="PullutionID">指標類型</param>        /// <returns></returns>        public static List<string> GetChartData(string StatioID, string PullutionID,string StartTime,string EndTime)        {            List<string> XData = new List<string>();            if (ConnectionString == null) OnCreateDB();            MoDataBase = MoClient.GetDatabase("SSMonitor");            BsonDocument bsonDoc = new BsonDocument();            bsonDoc.Add("TimeData", new BsonDocument() { { "$gte", DateTimeToInt(StartTime) }, { "$lte", DateTimeToInt(EndTime) } });            var collection = MoDataBase.GetCollection<BsonDocument>(string.Format("{0}_{1}_Day", StatioID, PullutionID));            var sort = Builders<BsonDocument>.Sort.Ascending("TimeData");            var list = collection.Find(bsonDoc).Sort(sort).ToList();            foreach (BsonDocument bsondoc in list)            {                string time = bsondoc.GetElement("MonitorTime").Value.ToString();                XData.Add(time);            }            return XData;        }

 

C#對MongDB取資料的常用代碼