This cheat sheet provides essential MongoDB commands for developers to efficiently manage and interact with their NoSQL databases. Whether you're a beginner or an experienced user, these commands will help you navigate common tasks from basic connection to advanced operations.

MongoDB Basics and Connection

Start by understanding how to connect to your MongoDB instance and manage databases and collections.

# *****************************************************************************
# BASICS
# *****************************************************************************

# Connect MongoDB Shell
mongo # connects to mongodb://127.0.0.1:27017 by default
mongo --host <host> --port <port> -u <user> -p <pwd> # omit the password if you want a prompt

# Show All Databases
show dbs

# Show Current Database
db

# Create Or Switch Database
use <database_name>

# Drop Database
db.dropDatabase()

# Create Collection
db.createCollection('posts')

# Show Collections
show collections

MongoDB CRUD Operations

Learn the fundamental Create, Read, Update, and Delete operations for managing data within your MongoDB collections.

# *****************************************************************************
# CRUD
# *****************************************************************************

# Insert Row
db.posts.insert({
  title: 'Post One',
  body: 'Body of post one',
  category: 'News',
  tags: ['news', 'events'],
  user: {
    name: 'John Doe',
    status: 'author'
  },
  date: Date()
})

# Insert Multiple Rows
db.posts.insertMany([
  {
    title: 'Post Two',
    body: 'Body of post two',
    category: 'Technology',
    date: Date()
  },
  {
    title: 'Post Three',
    body: 'Body of post three',
    category: 'News',
    date: Date()
  },
  {
    title: 'Post Four',
    body: 'Body of post three',
    category: 'Entertainment',
    date: Date()
  }
])

# Get All Rows
db.posts.find()

# Get All Rows Formatted
db.posts.find().pretty()

# Find One Row
db.posts.findOne({ category: 'News' })

# Find Rows
db.posts.find({ category: 'News' })

# Find Specific Fields
db.posts.find({ title: 'Post One' }, {
  title: 1,
  author: 1
})

# Update Row
db.posts.update({ title: 'Post Two' },
{
  title: 'Post Two',
  body: 'New body for post 2',
  date: Date()
},
{
  upsert: true
})

# Update Specific Field
db.posts.update({ title: 'Post Two' },
{
  $set: {
    body: 'Body for post 2',
    category: 'Technology'
  }
})

# Delete Row
db.posts.remove({ title: 'Post Four' })

Advanced MongoDB Functions

Explore more advanced functionalities like sorting, limiting, incrementing fields, and text search to enhance your data manipulation capabilities.

# *****************************************************************************
# OTHER FUNCTIONS
# *****************************************************************************

# Sort Rows
db.posts.find().sort({ title: 1 }).pretty() # asc
db.posts.find().sort({ title: -1 }).pretty() # desc

# Count Rows
db.posts.find().count()
db.posts.find({ category: 'news' }).count()

# Limit Rows
db.posts.find().limit(2).pretty()

# Chaining
db.posts.find().limit(2).sort({ title: 1 }).pretty()

# Foreach
db.posts.find().forEach(function(doc) {
  print("Blog Post: " + doc.title)
})

# Increment Field (\$inc)
db.posts.update({ title: 'Post Two' },
{
  $inc: {
    likes: 5
  }
})

# Rename Field
db.posts.update({ title: 'Post Two' },
{
  $rename: {
    likes: 'views'
  }
})

# Sub-Documents
db.posts.update({ title: 'Post One' },
{
  $set: {
    comments: [
      {
        body: 'Comment One',
        user: 'Mary Williams',
        date: Date()
      },
      {
        body: 'Comment Two',
        user: 'Harry White',
        date: Date()
      }
    ]
  }
})

# Find By Element in Array (\$elemMatch)
db.posts.find({
  comments: {
     $elemMatch: {
       user: 'Mary Williams'
       }
    }
  }
)

# Add Index
db.posts.createIndex({ title: 1 })

# Drop Index
db.posts.dropIndex("title_1")

# Hide/Unhide Indexes
db.posts.hideIndex("title_1")
db.posts.unhideIndex("title_1")

# Text Search
db.posts.find({
  $text: {
    $search: "\"Post O\""
    }
})

# Greater & Less Than
db.posts.find({ views: { $gt: 2 } })
db.posts.find({ views: { $gte: 7 } })
db.posts.find({ views: { $lt: 7 } })
db.posts.find({ views: { $lte: 7 } })

Further Resources

For more in-depth information on MongoDB, refer to the official documentation and community resources:

• MongoDB Official Documentation
• MongoDB Community
• MongoDB on Stack Overflow