November 2021
Intermediate to advanced
410 pages
12h 1m
Chinese
Content preview from MongoDB权威指南（第3版）
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136
｜
第
7
章
7.2
阶段入门
：
常见操作
为了开发聚合管道，我们将研究如何构建一些管道，其中包含你已经熟悉的操作。下面
会介绍
匹配
（
match
）、
投射
（
project
）、
排序
（
sort
）、
跳过
（
skip
）和
限制
（
limit
）这
5
个阶段。
要完成这些聚合示例，需要使用一个公司的数据集合。该集合中有许多字段，这些字段指
定了有关公司的详细信息，比如公司名称、公司简介以及公司成立的时间。
还有一些字段描述了公司已进行的数轮融资、公司的重要里程碑，以及该公司是否进行了
首次公开发行（
IPO
）
，如果是，那么其
IPO
的详细情况是什么。下面是一个包含
Facebook
公司数据的示例文档：
{
"_id" : "52cdef7c4bab8bd675297d8e",
"name" : "Facebook",
"category_code" : "social",
"founded_year" : 2004,
"description" : "Social network",
"funding_rounds" : [{
"id" : 4,
"round_code" : "b",
"raised_amount" : 27500000,
"raised_currency_code" : "USD",
"funded_year" : 2006,
"investments" : [
{
"company" : null,
"financial_org" : {
"name" : "Greylock ...
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I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.