汇总可能会得到单个结果吗? [英] Is it possible to get single result in aggregate?

问题描述

是否可以像db.collection.findOne一样在db.collection.aggregate上获得单个文档?

Is it possible to get a single document on db.collection.aggregate like as in db.collection.findOne?

推荐答案

可以添加 $match 阶段到聚合管道.但是，即使仅匹配一个文档，结果仍将是一个列表(在这种情况下，长度为一个).因此答案是"否，这是不可能的".

It is possible to add $match stage to aggregation pipeline. But even if it will match only one single document, then result will still be a list (of length one in that case). So the answer is "NO, it is not possible".

这篇关于汇总可能会得到单个结果吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！