MongoDB Cheat Sheet

February 2, 2021

3:56 am

MongoDB is a source-available cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with optional schemas.

to start server (mongod is mongo deamon)

mongod

to start shell

mongo

show dbs;

create/use database

Change database

use db_name;

show current database

db;

Collections are similar to table

show collections;

db.createCollection("students");

Drop collection/table

db.students.drop();

drop database

db.dropDatabase();

insertOne

db.students.insertOne({_id: 1, name: "shailesh"});

insertMany

db.students.insertMany([{_id: 2, name: "bagde"}, {_id: 3, name: "sheldon"}]);

count document

db.students.count();

select all documents/records

db.students.find();

select with projection

db.students.find({},{_id: 0});
db.students.find({},{name:0});

exists operator

db.students.find({age: {$exists: false}});

COMPARISON OPERATORS

in operator

db.students.find({_id: {$in: [2,3]}});

not equal operator

db.students.find({_id: {$ne: 2}});

equal operator

db.students.find({_id: {$eq: 2}});

less than $lt

less than equal $lte

greather than $gt

greater than equal $gte

LOGICAL OPERATORS

$and operator

db.students.find({$and : [{_id : {$gt:1}}, {_id: {$lt: 4}}]})

$or operator

db.students.find({$or : [{name : "bagde"}, {name: "shailesh"}]})

like case insensitive

db.students.find({name: /h/i})

exact match

db.students.find({name: /^BagDe$/i})

UPDATE

db.students.updateOne({_id: 1}, {$set : {age: 23}});
db.students.updateMany({age : {$exists: false}}, { $set : {age : 25}})

db.students.updateMany({}, {$set: {address: {city: "Mumbai", state: "MH"}}})
db.students.updateOne({_id: 4}, { $set : {address : {city: "Nagpur"}}});

Unset/Delete Fields

db.students.updateMany({}, {$unset : {city: ""}});

search within sub document

db.students.find({"address.city" : "Nagpur"}).pretty();

Delete Records

db.students.deleteOne({ $or : [{ age : {$lt : 25}}, {name : "sheldon"}] })

DISTINCT

db.students.distinct(“city”)

ORDER BY

db.students.find().sort({name: -1})

LIMIT

db.students.find().limit(10)
db.students.find().skip(5).limit(10)

Aggregation

Aggregate on all documents
db.emps.aggregate([{$group: {
	_id : null,
	total : {$sum : "$salary"},
	average : {$avg: "$salary"},
	min : {$min: "$salary"},
	max : {$max: "$salary"},
	count : {$sum: 1}	
}}]).pretty()


Aggregate on group by address
db.emps.aggregate([{$group: {
	_id : { address: "$address" },
	total : {$sum : "$salary"},
	average : {$avg: "$salary"},
	min : {$min: "$salary"},
	max : {$max: "$salary"},
	count : {$sum: 1}	
}}]).pretty()

ForEach Map

db.emps.find().forEach(x => { print(x.name) })

db.emps.find({salary: { $exists: -1 } }, {"salary": 1, _id: 0}).map(x => x.salary * 0.10)

MongoDB Assignment for Practice

var docs = [
{"name":"neha","contact_number":"9833910534","address":"mumbai","salary":30000,"employee_id":98821,"role":"manager"},
{"name":"mina","contact_number":"9833910535","address":"thane","salary":32000,"employee_id":98823,"role":"sales"},
{"name":"pankaj","contact_number":"9833910536","address":"bhopal","salary":40000,"employee_id":98824,"role":"hr"},
{"name":"mareena","contact_number":"9833910537","address":"meerut","salary":45000,"employee_id":98825,"role":"support"},
{"name":"pooja","contact_number":"9833910538","address":"delhi","salary":50000,"employee_id":98826,"role":"developer"},
{"name":"namita","contact_number":"9833910539","address":"surat","salary":52000,"employee_id":98820,"role":"sales"},
{"name":"sneha","contact_number":"9833910510","address":"baroda","salary":55000,"employee_id":98827,"role":"support"},
{"name":"anjali","contact_number":"9833910511","address":"ahmedabad","salary":60000,"employee_id":98828,"role":"tester"},
{"name":"harsha","contact_number":"9833910512","address":"mumbai","salary":20000,"employee_id":98829,"role":"operations"},
{"name":"varun","contact_number":"9833910512","address":"mehsana","salary":56000,"employee_id":98831,"role":"tester"},
{"name":"preeti","contact_number":"9833910513","address":"noida","salary":87000,"employee_id":98832,"role":"developer"},
{"name":"madhu","contact_number":"9833910525","address":"bangalore","salary":22000,"employee_id":98833,"role":"sales"}
];

db.createCollection("emps");
db.emps.insertMany(docs);
db.emps.find();

var docs = [{“name”:”neha”,”contact_number”:”9833910534″,”address”:”mumbai”,”salary”:30000,”employee_id”:98821,”role”:”manager”},{“name”:”mina”,”contact_number”:”9833910535″,”address”:”thane”,”salary”:32000,”employee_id”:98823,”role”:”sales”},{“name”:”pankaj”,”contact_number”:”9833910536″,”address”:”bhopal”,”salary”:40000,”employee_id”:98824,”role”:”hr”},{“name”:”mareena”,”contact_number”:”9833910537″,”address”:”meerut”,”salary”:45000,”employee_id”:98825,”role”:”support”},{“name”:”pooja”,”contact_number”:”9833910538″,”address”:”delhi”,”salary”:50000,”employee_id”:98826,”role”:”developer”},{“name”:”namita”,”contact_number”:”9833910539″,”address”:”surat”,”salary”:52000,”employee_id”:98820,”role”:”sales”},{“name”:”sneha”,”contact_number”:”9833910510″,”address”:”baroda”,”salary”:55000,”employee_id”:98827,”role”:”support”},{“name”:”anjali”,”contact_number”:”9833910511″,”address”:”ahmedabad”,”salary”:60000,”employee_id”:98828,”role”:”tester”},{“name”:”harsha”,”contact_number”:”9833910512″,”address”:”mumbai”,”salary”:20000,”employee_id”:98829,”role”:”operations”},{“name”:”varun”,”contact_number”:”9833910512″,”address”:”mehsana”,”salary”:56000,”employee_id”:98831,”role”:”tester”},{“name”:”preeti”,”contact_number”:”9833910513″,”address”:”noida”,”salary”:87000,”employee_id”:98832,”role”:”developer”},{“name”:”madhu”,”contact_number”:”9833910525″,”address”:”bangalore”,”salary”:22000,”employee_id”:98833,”role”:”sales”}];