(2)以cat_id分组,求sum db.goods.aggregate([{$match:{shop_price:{$gt:50}}},{$group:{_id:'$cat_id',sum:{$sum:1}}}]) 1. 4.查询每个栏目下的库存量(商品数量) db.goods.aggregate([{$group:{_id:"$cat_id",goods_total:{$sum:'$goods_number'}}}]) 1. 5.查询每个栏目下,价格大...
db.vehicles.aggregate([ {$set:{"specs.fuel_type":"unleaded"} } ] ) The operation returns the following results: {_id:1,type:"car",specs:{doors:4,wheels:4,fuel_type:"unleaded"} } {_id:2,type:"motorcycle",specs:{doors:0,wheels:2,fuel_type:"unleaded"} } ...
10]}}},]){"title":"MongoDB Aggregate","author":"liruihuan","newPages":15},{"title":"MongoDB Index","author":"liruihuan","newPages":13},{"title":"MongoDB Query","author":"eryueyang","newPages":18}
db.orders.aggregate([ # 第一阶段:$match阶段按status字段过滤文档,并将status等于"A"的文档传递到下一阶段。 { $match: { status: "A" } }, # 第二阶段:$group阶段按cust_id字段将文档分组,以计算每个cust_id唯一值的金额总和。 { $group: { _id: "$cust_id", total: { $sum: "$amount" }...
aggregate( {$group: { _id:'$字段名', 别名:{$聚合函数:'$字段名'} } } ); 例: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 # 统计同年龄的人数 db.yunfan_test.aggregate( {$group: { _id:'$age', count_age:{$sum:1} } } ); # 统计所有人平均年龄 db.yunfan_test.aggregate(...
例如,以下示例将返回年龄大于 25 岁的文档的平均年龄: db.collection.aggregate([{"$match": {"age": {"$gt":25}}},{"$group": {"_id":null,"avgAge": {"$avg":"$age"}}},{"$project": {"_id":false,"avgAge":true}}]) 1. 2. 3. 4. 5. 下表展示了一些聚合的表达式:...
aggregate:'table', pipeline: [ {$addFields: { totalNum: {$sum:"$num"} }}, {$project: { name:1,"$totalNum":1// 此处需要加$ }} ] } // 结果 // [{_id: 1, name: "aa", totalNum: 10}] $match,$limit,$skip,$count,$sort 不多介绍,看名字就知道什么意思 ...
db.collection_2023_3.aggregate( {$set:{_id:'2023_3'}}, {$unionWith:{coll:'collection_2023_4',pipeline:[ { $set: { _id: "2023_4" } } ]}} ) 2.多字段分组 { $group: { _id: { data_time: '$data_time', isoWeek: '$isoWeek' ...
db.vehicles.aggregate([ {$set:{"specs.fuel_type":"unleaded"} } ] ) The operation returns the following results: {_id:1,type:"car",specs:{doors:4,wheels:4,fuel_type:"unleaded"} } {_id:2,type:"motorcycle",specs:{doors:0,wheels:2,fuel_type:"unleaded"} } ...
以下代码实现了aggregate按日期分组统计并且当天没有数值的情况下自动补0. ReleaseCountResultVo.java package com.biologic.vo; import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date;