All basic mongoDB commands at one place.

all-mongodb-commands.md

Show All Created Databases

show dbs

Starte using the database named dbname

 use dbname

Show a collections inside a database

show collections

Delete/Drop a database

db.dropDatabase();

Create database if not exist and start using it

use dbname

Get the current databse

db;

Create a collection named posts

db.createCollection("posts");

Insert a post into posts collection

db.posts.insert({ name: "Shehan", age: 24 });

Insert many posts into posts collection

db.posts.insertMany([{}, {}, {}]);

Get all the posts

db.posts.find();

Show all posts in a pretty way

db.posts.find().pretty();

Sort all posts based on title to Ascending order

db.posts.sort({ title: 1 }).pretty();

Count the number os posts

db.posts.find({ category: "news" }).count();

Get only 2 posts (Limit the number of posts)

db.posts
  .find()
  .limit(2)
  .pretty();

#Get only 2 posts from the sorted posts

db.posts
  .find()
  .sort({ title: -1 })
  .limit(2)
  .pretty();

Print all the names of posts

db.posts.find().forEach(function(post) {
  print("Post" + post.name);
});

Get only one post from 'news' category

db.posts.findOne({ category: "news" });

Update a post, if not found, insert it

db.posts.update(
  { name: "Shehan" },
  { name: "Shay", age: 24 },
  { upsert: true }
);

Only update the specific part

db.posts.update({ name: "Shehan" }, { $set: { name: "Morgan", isMale: true } });

Increase age by 2

db.posts.update({ name: "Shehan" }, { $inc: { age: 2 } });

Rename 'age' to 'years'

db.posts.update({ name: "Shehan" }, { $rename: { age: years } });

Remove an instance

db.posts.remove({ name: "Shehan" });

Add sub documents

db.posts.update({ name: "Shehan" }, { $set: { skills: ["JavaScript"] } });

Find a document by sub document

db.users.find({ comments: { $elemMatch: { name: "Haily" } } }).pretty();

Creating an index

db.users.createIndex({ username: "text" });

Searching with Index

db.users.find({ $text: { $search: '"Moriah"' } }).pretty();

Greater than

db.users.find({ id: { $gt: 9 } }).pretty();

Greater than or Equal

db.users.find({ id: { $gte: 9 } }).pretty();

Lesser than

db.users.find({ id: { $lt: 9 } }).pretty();

Lesser than or Equal

db.users.find({ id: { $lte: 9 } }).pretty();