Mongodb InMongo db:-从下面的数据中，我需要得到最新的记录，其中所有字段都基于；“雇员ID”；及；alertTimeStamp"；

样本输入数据：-

 {
                "_id" : ObjectId("56069e78627e6c27e34d3613"),
                "employeeId" : 123456789,
                "alertTimeStamp" : ISODate("2015-09-21T11:59:09Z"),
                "cyclDt" : "2015-09-21",
                "emplcontactType" : "EML",
                "employeesalary" : 10000,
                "creatTimeStamp" : ISODate("2015-09-21T11:59:09Z"),
                "empmsgId" : 23456
        }
        {
                "_id" : ObjectId("56069e78627e6c27e34d3614"),
                "employeeId" : 123456789,
                "alertTimeStamp" : ISODate("2015-09-21T13:59:09Z"),
                "cyclDt" : "2015-09-21",
                "emplcontactType" : "EML",
                "employeesalary" : 10000,
                "creatTimeStamp" : ISODate("2015-09-21T13:59:09Z"),
                "empmsgId" : 23456
        }
        {
                "_id" : ObjectId("56069e78627e6c27e34d3615"),
                "employeeId" : 123456789,
                "alertTimeStamp" : ISODate("2015-09-21T15:59:09Z"),
                "cyclDt" : "2015-09-21",
                "emplcontactType" : "EML",
                "employeesalary" : 10000,
                "creatTimeStamp" : ISODate("2015-09-21T15:59:09Z"),
                "empmsgId" : 23456
        }

---

我还在下面运行分组查询，但没有了解如何检索所有字段（列）

---

在输出中，我应该只得到低于记录的数据

             {
                "_id" : ObjectId("56069e78627e6c27e34d3615"),
                "employeeId" : 123456789,
                "alertTimeStamp" : ISODate("2015-09-21T15:59:09Z"),
                "cyclDt" : "2015-09-21",
                "emplcontactType" : "EML",
                "employeesalary" : 10000,
                "creatTimeStamp" : ISODate("2015-09-21T15:59:09Z"),
                "empmsgId" : 23456
        }

---

请查收并告知。没有更多详细信息。

您的预期输出是什么？此处可能重复：

             {
                "_id" : ObjectId("56069e78627e6c27e34d3615"),
                "employeeId" : 123456789,
                "alertTimeStamp" : ISODate("2015-09-21T15:59:09Z"),
                "cyclDt" : "2015-09-21",
                "emplcontactType" : "EML",
                "employeesalary" : 10000,
                "creatTimeStamp" : ISODate("2015-09-21T15:59:09Z"),
                "empmsgId" : 23456
        }