步骤4: 执行聚合 接下来,我们需要把整个 Pipeline 传递给aggregate()方法,以执行聚合操作并获取结果。 // 执行聚合操作db.orders.aggregate(pipeline).toArray((err,result)=>{if(err){console.error("Error aggregating data:",err);}else{console.log("Total orders in 2023:",result);}}); 1. 2. 3. ...
db.order_item.aggregate([{ $project: { title: 1, price: 1 } }, { $match: { price: { $gte: 50 } } }, { $sort: { price: -1 } }, { $limit: 2 }]) // 限制返回两条数据 db.order_item.aggregate([{ $project: { title: 1, price: 1 } }, { $match: { price: { $gte...
The$countstage returns a count of the remaining documents in the aggregation pipeline and assigns the value to a field calledpassing_scores. db.scores.aggregate( [ { $match:{ score:{ $gt:80 } } }, { $count:"passing_scores" }
1. 大于,小于,大于或等于,小于或等于,不等于2. value是否在List中:in 和 not in3. 判断元素是否存在exists4.selectdistinct的实现:5.查询嵌入对象的值6.数组大小匹配size7. 全部匹配 本博客将列举一些常用的MongoDB操作,方便平时使用时快速查询,如find, count, 大于小于不等, select distinct, groupby等 ...
This example uses$countin the$setWindowFieldsstage to count the number of documents in thecakeSalescollection for eachstatedefined in thewindow: db.cakeSales.aggregate( [ { $setWindowFields: { partitionBy:"$state", sortBy: {orderDate:1}, ...
MongoDB的蠢萌的索引使用能力，简直了，group之后就直接瞎了不会用了，unwind之后也瞎。而那个所谓的...
To avoid these situations, on a sharded cluster, use the $group stage of the db.collection.aggregate() method to $sum the documents. For example, the following operation counts the documents in a collection: db.collection.aggregate([{$group:{_id:null,count:{$sum:1}}}]) ...
mongos> var match ={"$match":{"count" : {"$gt" : 1}}}; mongos>3 获取数据mongos> db.stu.aggregate(group, match); { "result" : [ { "_id" : 2, "max_age" : 17, "count" : 5 }, { "_id" : 1, "max_age" : 14, "count" : 4 }, { "_id" : 3, "max_age" ...
To avoid these situations, on a sharded cluster, use thegroupstageofthedb.collection.aggregate()methodtosum the documents. For example, the following operation counts the documents in a collection: 为了避免分片集群发生这种情况,使用db.collection.aggregate()命令中的group方法进行文档sum求和。例如以下对...
Microsoft Copilot for Azure in Cosmos DB (preview) Clauses Working with JSON Subquery Joins Arrays and objects Keywords Constants Scalar expressions Computed properties Operators Aggregate functions AVG COUNT MAX MIN SUM System functions Geospatial data ...