Mongo-DB CheatSheet for Developers

Database Commands

Command	Description
createUser	Creates a new user.
show dbs	View all databases
use dbName	Create a new or switch databases
db	View current Database
db.dropDatabase()	Delete Database
usersInfo	Returns information about the specified users.

Collection Commands

Command	Description
db.createCollection('collection_name')	Create a collection named 'collection_name'
db.collection_name.drop()	Drop a collection named 'collection_name'

Row(Document) Commands

Command	Description
db.collection_name.find()	Show all Rows in a Collection
db.collection_name.find().pretty()	Show all Rows in a Collection (Prettified)
db.collection_name.findOne({name: 'ritwik'})	Find the first row matching the object
db.collection_name.insert({'name': 'Ritwik','lang': 'sql','member_since': 5 })	Insert One Row
db.collection_name.insertMany([{'name': 'Ritwik','lang': 'sql','member_since': 5}, {'name': 'Rohan','lang': 'Python','member_since': 3},{'name': 'Lovish','lang': 'Java','member_since': 4}])	Insert many Rows
db.collection_name.find({lang:'Python'})	Search in a MongoDb Database
db.collection_name.find().limit(2)	Limit the number of rows in output
db.collection_name.find().count()	Count the number of rows in the output
db.collection_name.updateOne({name: 'Shubham'},{$set: {'name': 'Harry','lang': 'JavaScript','member_since': 51}},{upsert: true})	Update a row
db.collection_name.update({name: 'Rohan'},{$inc:{member_since: 2}})	Mongodb Increment Operator
db.collection_name.update({name: 'Rohan'},{$rename:{member_since: 'member'}})	Mongodb Rename Operator
db.collection_name.remove({name: 'Harry'})	Delete Row
db.collection_name.deleteOne({name: 'Harry'})	Delete one Row
db.collection_name.deleteMany({lang: 'JavaScript'})	Delete many Row

MongoDB Query Operators

There are many query operators that can be used to compare and reference document fields.

Comparison Operators

The following operators can be used in queries to compare values:

Command	Description
$eq	Values are equal
$ne	Values are not equal
$gt	Value is greater than another value
$gte	Value is greater than or equal to another value
$lt	Value is less than another value
$lte	Value is less than or equal to another value
$in	Value is matched within an array

Logical Operators

The following operators can logically compare multiple queries.

Command	Description
$and	Returns documents where both queries match
$or	Returns documents where either query matches
$nor	Returns documents where both queries fail to match
$not	Returns documents where the query does not match

Evaluation Operators

The following operators assist in evaluating documents.

Command	Description
$regex	Allows the use of regular expressions when evaluating field values
$text	Performs a text search
$where	Uses a JavaScript expression to match documents

MongoDB Update Operators

There are many update operators that can be used during document updates.

Fields

The following operators can be used to update fields:

Command	Description
$currentDate	Sets the field value to the current date
$inc	Increments the field value
$rename	Renames the field
$set	Sets the value of a field
$unset	Removes the field from the document

Array

The following operators assist with updating arrays.

Command	Description
$addToSet	Adds distinct elements to an array
$pop	Removes the first or last element of an array
$pull	Removes all elements from an array that match the query
$push	Adds an element to an array

MongoDB - Aggregation

Expression	Description
$sum	Sums up the defined value from all documents in the collection.
$avg	Calculates the average of all given values from all documents in the collection.
$min	Gets the minimum of the corresponding values from all documents in the collection.
$max	Gets the maximum of the corresponding values from all documents in the collection.
$push	Inserts the value to an array in the resulting document.
$addToSet	Inserts the value to an array in the resulting document but does not create duplicates.
$first	Gets the first document from the source documents according to the grouping. Typically this makes only sense together with some previously applied “$sort”-stage.
$last	Gets the last document from the source documents according to the grouping. Typically this makes only sense together with some previously applied “$sort”-stage.