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MongoDB

"MongoDB is a general purpose, document-based, distributed database built for modern application developers and for the cloud era. No database makes you more productive."

Starting and Stopping

brew services start mongodb-community@4.4
brew services stop mongodb-community@4.4

MongoDB Atlas

"MongoDB Atlas is the global cloud database service for modern applications. Deploy fully managed MongoDB across AWS, Azure, or GCP. Best-in-class automation and proven practices guarantee availability, scalability, and compliance with the most demanding data security and privacy standards. Use MongoDB's robust ecosystem of drivers, integrations, and tools to build faster and spend less time managing your database."

https://www.mongodb.com/cloud/atlas

Element Operators

  • $exists - checks for the existence of a given key
  • $type - returns the type of a given a key

Connecting to the Sample Databases

Connecting to the Mongo University sample datasets in either Compass or via the shell...

mongo "mongodb+srv://cluster0-jxeqq.mongodb.net/test" --username m001-student -password m001-mongodb-basics

mongo "mongodb://cluster0-shard-00-00-jxeqq.mongodb.net:27017,cluster0-shard-00-01-jxeqq.mongodb.net:27017,cluster0-shard-00-02-jxeqq.mongodb.net:27017/test?replicaSet=Cluster0-shard-0" --authenticationDatabase admin --ssl --username m001-student --password m001-mongodb-basics

Connecting to my Cluster

dbUser PvCcAnLlJM5EIAoz mongo "mongodb+srv://cluster0-vafgz.mongodb.net/test" --username dbUser

mongodb+srv://dbUser:PvCcAnLlJM5EIAoz@cluster0-vafgz.mongodb.net/test

Guides

https://university.mongodb.com/exam/guide#crud

Data Types

  • integer
  • double
  • string
  • bool
  • date
  • object (document)
  • array

Nesting documents

You can go as many levels deep with nested documents

Geospatial data

Note that geospatial is a type per se (e.g. it's just an array type with two doubles) there's a ton of support build into MongoDB, Compass, etc for working with it.

Querying

All about filtering...lots of filtering types, e.g. equality, range, etc.

  • eq - equality
  • gte - greater than or equal to
  • lte - less than or equal to

Example queries

{'end station name': 'Broadway & E 22 St', 'birth year': {$gte: 1960,$lt: 1965}

{tripduration: {'$gte': 60, '$lt': 65}}

Note that $gte and $lte are called operators.

If you pass multiple criteria in the same query document they are implicitly “ANDED” together.

Querying Embedded Documents

Dot notation is used to query nested documents.

dbName.collectionName.find({wind.type: “N”})

Querying Against Arrays

A few points to note:

  • For searching for just a single element it’s the same syntax of that of a document
  • For multiple elements, you can pass in an array (e.g. { "cast": [“Jeff Bridges", “John Locke”] }) although not this will look for these elements in this exact order.
  • Is you want to search for an element for at a specific position / index in an array you can use the following: { "cast.0": "Jeff Bridges" }

Projections

Projections allow you to explicitly specify the fields you’d like returns. You pass a second argument in the .find function and then pass a 0 or 1 against the field names to exclude or include respectively.

CRUD

Create, Read, Update, Delete

show dbs
use xyzzy
show collections

Insertion

collectionName.insertOne({...})

Note that every document has an _id automatically created for it. Guaranteed to be unique and “increasing”. Note that you can provide your own _id too.

collectionName.insertMany([{...},{...}], {“ordered”, true | false})

Insert many allows you to insert multiple documents simultaneously. Note that the optional ordered parameter determines whether it stops if it encounters duplicates.

Misc.

mongo “mongodb://cluster0-shard-00-00-jxeqq.mongodb.net:27017,cluster0-shard-00-01-jxeqq.mongodb.net:27017,cluster0-shard-00-02-jxeqq.mongodb.net:27017/aggregations?replicaSet=Cluster0-shard-0” —authenticationDatabase admin —ssl -u m121 -p aggregations —norc …. showcollections

https://university.mongodb.com/mercury/M121/2020_May_19/chapter/Chapter_1_Basic_Aggregation_-_match_and_project/lesson/5970d8b78cf2c5580eef7d8b/problem

mongo “mongodb+srv://cluster0-vafgz.mongodb.net:27017/test” —username dbUser —password PvCcAnLlJM5EIAoz

MongoDB delete example … load I. The videos dB … https://s3.amazonaws.com/edu-downloads.10gen.com/M001/2020/May/static/handouts/loadReviewsDataset.zip

sudo apt-get install -y mongodb

MongoDB screenshots folder in Photos / visit the Mongo docs for update operators and try a few (and add to notes)…also refactor the CRUD section /// updateMany useful for data cleaning

MongoDB - UpdateOne vs ReplaceOne