Notes from the MongoDB introductory tutorial present at http://try.mongodb.org

tryMongoDB.js

// This is the MongoDB tutorial from http://try.mongodb.org

// Get started with `help`
// To try out an interactive tutorial type `tutorial`

// This shell is a (limited) javascript interpreter, so any commands you are familiar from javascript should work here.  Try out: 
  var a = 5;
  a * 10;
  for(i=0; i<10; i++) { print('hello'); };
// You can move onto the next step anytime by typing `next` 
 
// MongoDB is a document database. This means that we store data as documents, which are similar to JavaScript objects. Here below are a few sample JS objects:
  var a = {age: 25};
  var n = {name: 'Ed', languages: ['c', 'ruby', 'js']};
  var student = {name: 'Jim', scores: [75, 99, 87.2]};
// Go ahead and create some documents, then enter 'next'
 
// Here's how you save a document to MongoDB:
  db.scores.save({a: 99});
// This says, "save the document '{a: 99}' to the 'scores' collection.".
// To confirm that it's been saved properly:
  db.scores.find();
 
// Try adding some documents to the scores collection:
  for(i=0; i<20; i++) { db.scores.save({a: i, exam: 5}) };
// Try that, then enter
  db.scores.find();
// to see if the save succeeded. Since the shell only displays 10 results at time, you'll need to enter the 'it' command to iterate over the rest.
 
// You've already tried a few queries, but let's make them more specific.
// Let's find all documents where a == 2:
  db.scores.find({a: 2});
// Or we could find all documents where a > 15:
  db.scores.find({a: {'$gt': 15}})
 
// `$gt` is one of many special query operators. Here are few others:
  {a: {$lt: 5}} // Less Than
  {a: {$gte: 10}} // Greater than or equal to
  {a: {$ne: 'b'}} // Not Equal To
  {a: {$in: ['a', 'b', 'c']}} // Exists in array
// Try out a few queries, before moving onto the next step.
 
// Now create a couple documents like these for updating:
  db.users.insert({name: 'Johnny', languages: ['ruby', 'c']});
  db.users.insert({name: 'Sue', languages: ['scala', 'lisp']});
// Confirm they were saved - with our favorite:
  db.users.find()
// Update Johnny's name and languages: 
  db.users.update({name: 'Johnny'}, {name: 'Cash', languages: ['English']});
// Use our favorite find query to inspect the resulting documents.  Notice that the array update overwrote Johnny's languages!
// Play with some more updates, before continuing on.
 
// Update has the sometimes unexpected behavior of replacing the entire document.  However, we can use update operators to only modify parts of our documents.
// Update Sue's languages without overwriting them:
  db.users.update({name: 'Sue'}, { $addToSet: {languages: 'ruby'}});
// Or we can add a new field to Cash
  db.users.update({name: 'Cash'}, {'$set': {'age': 50} });
// You can also push and pull items from arrays:
  db.users.update({name: 'Sue'}, {'$push': {'languages': 'ruby'} });
  db.users.update({name: 'Sue'}, {'$pull': {'languages': 'scala'} });
// Give these a try, check the results, and then enter 'next',
 
// To delete matching documents only, add a query selector to the remove method:
  db.users.remove({name: 'Sue'});
// To delete everything from a collection:
  db.scores.remove({});
 
// Congratulations! You've reached the end of this simple tutorial.
// Now take the next step with free MongoDB Online training at MongoDB University - university.mongodb.com!