MongoDB CheatSheet | Professional Reference

Core Commands

show dbs

Lists all available databases on the server.

mongo> show dbs

use <db>

Switches context to a specific database.

mongo> use products

Displays the name of the current database.

mongo> db

db.stats()

Provides storage statistics for current DB.

mongo> db.stats()

db.dropDatabase()

Permanently deletes the current database.

mongo> db.dropDatabase()

db.version()

Returns the MongoDB server version.

mongo> db.version()

show collections

Lists all collections in the current DB.

mongo> show collections

db.createCollection()

Manually creates a new collection.

db.createCollection("users")

CRUD Operations

insertOne()

Adds a single document to a collection.

db.users.insertOne({name: "John"})

insertMany()

Inserts an array of documents.

db.users.insertMany([{...}, {...}])

updateOne()

Updates first matching document.

db.users.updateOne({id: 1}, {$set: {age: 25}})

updateMany()

Updates all matching documents.

db.users.updateMany({active: true}, {...})

deleteOne()

Removes a single matching document.

db.users.deleteOne({id: 1})

replaceOne()

Replaces matching document entirely.

db.users.replaceOne({id: 1}, {new: "doc"})

Query Basics

find()

Query all or filtered documents.

db.users.find({age: {$gt: 18}})

findOne()

Returns first matching document only.

db.users.findOne({email: "..."})

sort() / limit()

Order results and constrain count.

find().sort({name: 1}).limit(5)

countDocuments()

Get accurate count of filtered docs.

db.users.countDocuments({age: 20})

distinct()

Find all unique values for a field.

db.users.distinct("city")

explain()

Analyzes performance of query execution.

db.users.find().explain("executionStats")

Query Operators

Operator	Definition	Example
$gt / $lt	Greater than / Less than comparison	`{age: {$gt: 21}}`
$in	Matches any value in the provided array	`{tags: {$in: ["A", "B"]}}`
$and / $or	Logical JOIN of multiple conditions	`{$or: [{age: 5}, {age: 10}]}`
$elemMatch	Matches criteria in array elements	`{scores: {$elemMatch: {$gt: 80}}}`
$text	Performs search on text-indexed fields	`{$text: {$search: "coffee"}}`

Update Operators

Operator	Definition	Example
$set / $unset	Sets field value / Removes field	`{$set: {status: "A"}}`
$inc / $mul	Increment / Multiply numeric values	`{$inc: {count: 1}}`
$push / $pull	Add or remove values from an array	`{$push: {tags: "New"}}`
$addToSet	Adds to array only if value unique	`{$addToSet: {tags: "unique"}}`

Aggregation Pipeline

Stage	Definition	Example
$match	Filters documents (reduces dataset)	`{$match: {status: "A"}}`
$group	Groups documents by specified ID	`{$group: {_id: "$cat"}}`
$project	Shapes documents (renaming/adding)	`{$project: {name: 1}}`
$lookup	Left outer join to another collection	`{$lookup: {from: "orders"}}`
$unwind	Deconstructs array field to documents	`{$unwind: "$sizes"}`

Administration & Management

Command	Definition	Example
createIndex()	Optimizes query performance	`db.col.createIndex({f: 1})`
currentOp()	Lists currently running operations	`db.currentOp()`
watch()	Opens change stream for real-time tracking	`db.col.watch()`
hostInfo()	System and host diagnostic info	`db.hostInfo()`

mongodump / mongorestore

High-performance BSON backup and restore utilities for database migration and disaster recovery.

mongodump --db test --out /backup/

mongoexport / mongoimport

Export or import data into JSON, CSV, or TSV formats for integration with third-party tools.

mongoexport --db users --collection log --out log.json