MongoDB Tutorial 0/120 lessons ~6 min read Lesson 49“Document-first database engineering”

Group Stage

$group is the SQL GROUP BY of MongoDB.

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Focus

2 guided sections

Practice signal

Concept-first lesson

Career prep

Foundation builder

Introduction

$group is the SQL GROUP BY of MongoDB. It groups documents by a key and computes accumulators ($sum, $avg, $min, $max, $push) per group.

Syntax reference

{ $group: {
  _id: "$category",
  totalRevenue: { $sum: "$amount" },
  avgOrder:     { $avg: "$amount" },
  count:        { $sum: 1 }
}}

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