MongoDB sum()数据 [英] MongoDB sum() data

问题描述

我是mongoDB和nosql的新手，获取总和的语法是什么?

I am new to mongoDB and nosql, what is the syntax to get a sum?

在MySQL中，我将执行以下操作:

In MySQL, I would do something like this:

SELECT SUM(amount) from my_table WHERE member_id = 61;

我如何将其转换为MongoDB?这是我尝试过的:

How would I convert that to MongoDB? Here is what I have tried:

db.bigdata.aggregate({
    $group: {
        _id: {
            memberId: 61, 
            total: {$sum: "$amount"}
        }
    }
})

推荐答案

使用 http://docs.mongodb.org/manual/tutorial/aggregation-zip-code-data-set/以供您参考:

db.bigdata.aggregate(
{
    $match: {
        memberId: 61
    }
},
{
    $group: {
        _id: "$memberId",
        total : { $sum : "$amount" }
    }
})

来自MongoDB文档:

From the MongoDB docs:

聚合管道是一个基于数据处理管道概念建模的数据聚合框架.文档进入多阶段流水线，将文档转换成汇总结果.

The aggregation pipeline is a framework for data aggregation modeled on the concept of data processing pipelines. Documents enter a multi-stage pipeline that transforms the documents into an aggregated results.

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