MongoDB Basics

Basic Commands

• show dbs Show databases
• use dbName Connect/Select database
• use dbName Create database (MongoDB doesn’t actually create a db until we start storing documents, so although you now have the db bookmarks, it’s not actually saved anywhere until we put some data in it. Same goes for collectons )
• db show the db you are using
• doc show the document content

NoSQL Database Terms

Adding Data

There are two methods. One uses .insert()

1db.links.insert({ title: "Courses", url: "http://tutsplus.com", comment: "advanced programming video courses", tag: ["tutorials", "dev "], saved_on: new Date() });

and the other us saving an empty document and then adding data to it. e.g:

1var doc = {};
2doc.title = '';
3doc.url = '';
4doc.comment = '';
5doc.tags = '';
6doc.saved_on = new Date; 

adding sub-objects inside of objects

1doc.meta = {}
2doc.meta.browser = 'Google Chrome 31'
3doc.meta.OS = 'Mac OS 10.9.2'

Saving and Updating data

• db.links.save(doc) save all data in the doc collection to the links database
• db.links.update()

Methods

• .insert() add data
• .count() show the number of collections/documents
• .date() shows the date the data was entered
• .find() find with no parameters given will just output all data, e.g: - db.links.find()
• .save()
• .update()
• .forEach(printjson); print documents nicely formatted e.g: db.links.find()- .forEach(printjson);
• .getTimestap() use this method on an _id to get the time the object was created.

Object IDs

This _id or ObjectId object field is immutable and unique. You can’t have two documents with the same _id

• 12 byte value
• BSON data type
• based on the hostname of the machine, the prcess id of the server process, the time the record was saved and a random incrementing number.
• since they are based on the time they are created, we can get the time an object was created by its ID. We don’t need the created_at or saved_at fields in MongoDB because the ID already has that info.