Mongo Database Basics. As of Mongo version 3.4.1

• Install mongodb brew install mongodb
• make data directory sudo mkdir -p /data/db
• To get mongo dameon up and running sudo mongod
• Access mongo shell with mongo
• close mongodb with ctrl + c twice in stop Database
• list database with show dbs
• To create new database with use command ie use mongoBasics
• Create user for database:

  db.createUser(
     {
       user: "admin",
       pwd: "somepassword",
       roles: [ "readWrite", "dbAdmin" ]
     }
  );
  

• To update user use db.updateUser()
• Login as user: db.auth('user','password');
• Get mongodb version db.version()

Working with Mongo

• See contents of current directory ls()
• Load file in directory with load('./seed.js')
• the following is the same as running use mongoBasics from the db.getSiblingDB('mongoBasics');
• Find length of collection with db.collectionname.count()
• Query collection with db.collectionname.find() or at specific document with db.collectionname.find()[1]
• Limit number of posts with db.collectionname.find().limit(2)
• Assign collections to variables easily with var data = db.collectionname.find() and access with data.item
• Only return certain data from a collection with bolleans db.collectionname.find({}, {body: false, description: false}) or instead of ommiting fields get one field back with db.collectionname.find({}, {title:true}) and to turn id off do db.collectionname.find({}, {title:true, id:false})
• To query for a certain value do db.collectionname.find({title: "some title"},{})
• For more query operators visit https://docs.mongodb.org/v3.0/reference/operator/query/
• To insert data do db.post.insert. ie db.post.insert({"title": "horray!"})
• Use show dbs to see a list of databases. To see collections use show collections and to see items in collection db.post.find()
• To update posts do db.posts.update({"author": ObjectId("584c605def2992d45926dd74")},{$set:{tags: ['foo', 'bar', 'interesting']}})
• See what keys are in a field collection Object.keys(db.posts.find()[0])
• To sort asccending/decending use sort db.posts.find({}, {title:true}).sort({title: 1}) and decending db.posts.find({}, {title:true}).sort({title: -1})

• For pagination results use limit and skip methods db.posts.find({}, {title:true}).limit(2).skip(2)

  • Pagination formula: limit = number of records on each page, skip = number of records on each page * page number - 1

  • So, with 5 results per page:

  • page 1: limit = 5, skip = 0
  • page 2: limit = 5, skip = 5
  • page 3: limit = 5, skip = 10
  • etc...

Mongo drivers

• for node.js there is a core MongoDB driver or the popular Mongoose driver
• For PHP there is PHPLIB+ driver
• more here https://docs.mongodb.com/ecosystem/drivers

Mongo extras

• For shell syntax highlighting install npm install -g mongo-hacker
• Mongo is more powerful compared to relational databases because of sharding https://docs.mongodb.org/manual/sharding/