MongoDB Cheat Sheet

I’ve been working with MongoDB since the beginning of my career, and I finally decided to put together a cheat sheet— I’ve created for myself and others who might need a quick reminder.

While brushing up on MongoDB recently, I realized how helpful it would be to have everything in one place. So here it is—a handy, practical reference that I’ll keep updating as I go.

Hope you find it useful!

🔹 Basic Commands

show dbs                    // List all databases
use dbName                  // Switch to (or create) a database
show collections            // List all collections in the current DB

🔹 Inserting Data

db.collection.insertOne({name: "Ram"})
db.collection.insertMany([{name: "John"}, {name: "Jane"}])

🔹 Reading Data

db.collection.find()                              // Find all documents
db.collection.findOne({name: "Ram"})              // Find one document
db.collection.find().limit(5)                     // Limit number of results
db.collection.find().forEach(doc => print(doc))   // Loop through documents
db.collection.countDocuments()                    // Count documents

🔹 Updating Data

db.collection.updateOne(
  { name: "Ram" },
  { $set: { idCards: { hasPancard: true, hasAdharCard: true } } }
)

db.collection.updateMany(
  {},
  { $set: { hobbies: "anime" } }
)

🔹 Deleting Data

db.collection.deleteOne({ name: "Ram" })
db.collection.deleteMany({})  // Deletes all documents in collection

🔹 Query Operators

$lt   // Less than
$lte  // Less than or equal to
$gt   // Greater than
$gte  // Greater than or equal to
$in   // Matches any value in an array
$nin  // Not in
$not  // Not operator
$and  // Logical AND
$or   // Logical OR
$nor  // Logical NOR

🔹 Other Useful Commands

db.collection.drop()   // Drop a collection
db.dropDatabase()      // Drop the current database

🔹 Concepts

• Schemaless: MongoDB collections don’t enforce document structure.

• Data types: String, Number, Boolean, Array, Object, Date, etc