Cheat Sheet for Mongodb with essential commands

mongodb_cheat_sheet.md

MongoDB Cheat Sheet

Show All Databases

show dbs

Show Current Database

db

Create Or Switch Database

use acme

Drop

db.dropDatabase()

Create Collection

db.createCollection('posts')

Show Collections

show collections

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.find().pretty()

Find Rows

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

Sort Rows

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

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)
})

Find One Row

db.posts.findOne({ 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',  // since $set: {} is not use, this will delete all the formal fields then replace field currently listed
  body: 'New body for post 2',
  date: Date()
},
{
  upsert: true  // it means create a document if does not exist with the following detail or just update record with
                // title`: 'Post Two'
})

Update Specific Field

db.posts.update({ title: 'Post Two' },
{
  $set: {. // this will update only specific field listed inside $set: {}
    body: 'Body for post 2',
    category: 'Technology'
  }
})

Increment Field ($inc)

db.posts.update({ title: 'Post Two' },
{
  // $inc is use to increase a particular field which number specified is added to earlier figure it has
  $inc: {
    likes: 5
  }
})

Rename Field

db.posts.update({ title: 'Post Two' },
{
  // $rename is use to rename field
  $rename: {
    likes: 'views'
  }
})

Delete Row

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

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: 'text' }) //createIndex is use to create search value which the db can be queried with e.g text

Text Search

db.posts.find({
  // $text is the index created which is tied to title column which will be use to search all title fields of the db & return
  // where the title field match inputted value of the $search keyword 
  $text: {
    $search: "\"Post O\""
    }
})

Greater & Less Than

db.posts.find({ views: { $gt: 2 } })   // $gt means greater than
db.posts.find({ views: { $gte: 7 } })  // $gt means greater than or equal to
db.posts.find({ views: { $lt: 7 } })   // $lt means less than or equal to
db.posts.find({ views: { $lte: 7 } })  // $lt means less than or equal to