MongoDb 求和查询
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/18969916/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
MongoDb sum query
提问by user2597504
For example I have the following data in MongoDB:
例如，我在 MongoDB 中有以下数据：
{ "_id" : ObjectId("524091f99c49c4c3f66b0e46"), "hour" : 10, "incoming", 100}
{ "_id" : ObjectId("5240a045dbeff33c7333aa51"), "hour" : 11, "incoming", 200}
{ "_id" : ObjectId("5240a2ecda0d37f35c618aca"), "hour" : 12, "incoming", 300}
Now I want to query "SUM the number of incoming between 11 - 12" (the result should be 500), how could I do this using Mongo Shell?
现在我想查询“SUM 11 - 12 之间的传入数量”（结果应该是 500），我怎么能用 Mongo Shell 做到这一点？
回答by jamshehan
As llovet suggested, the aggregation framework is the way to go. Here's what your query would look like:
正如 lllovet 所建议的，聚合框架是要走的路。您的查询如下所示：
db.CollectionNameGoesHere.aggregate({ $match: {
$and: [
{ hour: { $gte: 11 } },
{ hour: { $lte: 12 } }
]
} },
{ $group: { _id : null, sum : { $sum: "$incoming" } } });
You can also shape the resulting document to only contain the sum by adding a $project operator at the end of the pipeline, like so:
您还可以通过在管道末尾添加 $project 运算符来将生成的文档整形为仅包含总和，如下所示：
{ $project: { _id: 0, sum: 1 } }
回答by yaya
Some examples if you use mongoose:
如果您使用mongoose 的一些示例：
- Calculate total sum of product prices :
- 计算产品价格的总和：
Products.aggregate([ { $match: {} }, { $group:
{ _id : null, sum : { $sum: "$Price" } }
}])
.then(res => console.log(res[0].sum));
( { $match: {} },can be removed. )
（{ $match: {} },可以删除。）
- Sum of Product's prices in each category:
- 每个类别的产品价格总和：
Products.aggregate([{ $group:
{ _id : '$Category', sum : { $sum: "$Price" } }
}])
.then(res => console.log(res));
