在 nodeJS 和 MongoDb 的集合中查找最大值

Posted 2023-03-16

【中文标题】在 nodeJS 和 MongoDb 的集合中查找最大值

【英文标题】：Find a maximum value in a collection in nodeJS and MongoDb

【发布时间】：2014-04-13 11:08:54

【问题描述】：

我有一个非常简单的查询，但无法正常工作。 我有一个名为 users 的集合，其中包含 uid 字段。 我想从中获取 uid 字段的最大值。 以下是我所做的：-

   var options =  "sort": [['uid',-1]] ;
    db.users.findOne(, options , function(err, doc) 
    console.log("Returned #" + doc.uid + " documents");
); 

但这给了我 99，而我的值高达 300。 我猜它是将每个元素与 9 匹配，然后进行比较。 正确答案应该是 314

以下是条目保存在集合中的方式：-

 
 
 _id: "531181a3ec9af9107d2b4ccd",
 age: "0",
 carModel: "bullet motorcycle",
 chargePrice: "",
 contact: "",
 email: "",
 fbid: "1179803227",
 fromLat: "28.4594965",
 fromLon: "77.0266383",
 fromName: "Gurgaon, Haryana, India",
 fuelType: "Petrol",
 id: "215",
 image: "http://graph.facebook.com/1179803227/picture?type=large",
 name: "Sandeep Yadav",
 points: "0",
 regid: "abc",
 returnTime: "15:41 Hrs",
 sex: "0", 
 smoking: "No Smoking allowed",
 startTime: "15:41 Hrs",
 toLat: "28.510782",
 toLon: "77.048646",
 toName: "Sector 23 ,HUDA Market, Huda, Sector 23, Gurgaon, Haryana, India",
 uid: 311
,

 _id: "531181a3ec9af9107d2b4cce",
 age: "0",
 carModel: "2014 Nissan sentra",
 chargePrice: "USD 30",
 contact: "",
 email: "",
 fbid: "100001451156666",
 fromLat: "27.950575",
 fromLon: "-82.4571776",
 fromName: "Tampa, FL, United States",
 fuelType: "Petrol",
 id: "214",
 image: "http://graph.facebook.com/100001451156666/picture?type=large",
 name: "Kelly J. Dugan",
 points: "0",
 regid: "abc",
 returnTime: "23:04 Hrs",
 sex: "0",
 smoking: "Doesnt Matter",
 startTime: "16:02 Hrs",
 toLat: "25.7889689",
 toLon: "-80.2264393",
 toName: "Miami, FL, United States",
 uid: 308

【问题讨论】：

Using findOne in mongodb to get element with max id 的可能重复项

【参考方案1】：

试试这个：

db.users.find().sort("uid":-1).limit(1)

这将找到所有用户，然后对它们进行排序，然后只返回第一个。