By Neal Tyler Queen in MongoDB — Apr 7, 2024

MongoDB Cheat Sheet

This MongoDB cheat sheet in Markdown format that covers essential commands and concepts for working with MongoDB, including basic operations, query techniques, aggregation framework, indexing, and database management.

Basic Operations

Start MongoDB Server
```
mongod
```
Connect to MongoDB
```
mongo
```

Database Operations

Show Databases
```
show dbs
```
Create or Switch Database
```
use db_name
```
Drop Database
```
db.dropDatabase()
```

Collection Operations

Show Collections
```
show collections
```
Create Collection
```
db.createCollection('collection_name')
```
Drop Collection
```
db.collection_name.drop()
```

Document Operations

Insert Document

db.collection_name.insert({key: 'value'})

Insert Multiple Documents

db.collection_name.insertMany([{key1: 'value1'}, {key2: 'value2'}])

Find Documents

db.collection_name.find({key: 'value'})

Find One Document

db.collection_name.findOne({key: 'value'})

Update Document

db.collection_name.update({key: 'value'}, {$set: {key_updated: 'new_value'}})

Delete Document

db.collection_name.remove({key: 'value'})

Querying

Equality

db.collection_name.find({key: 'value'})

Less Than / Greater Than

db.collection_name.find({key: {$lt: value}}, {key: {$gt: value}})

Logical AND

db.collection_name.find({$and: [{key1: 'value1'}, {key2: 'value2'}]})

Logical OR

db.collection_name.find({$or: [{key1: 'value1'}, {key2: 'value2'}]})

Aggregation

Group By

db.collection_name.aggregate([{ $group: {_id: "$key", total: { $sum: 1}}}])

Match

db.collection_name.aggregate([{ $match: {key: 'value'}}])

Project

db.collection_name.aggregate([{ $project: {key1: 1, key2: 1}}])

Indexing

Create Index

db.collection_name.createIndex({key: 1})

List Indexes
```
db.collection_name.getIndexes()
```

Drop Index

db.collection_name.dropIndex('index_name')