MongoDB Tutorial

# Start the command shell
.../bin/mongo
> show dbs
> show collections

# Remove collection
> db.person.drop()

# Stop the Mongod server from shell
> use admin
> db.shutdownServer()

# create a doc and save into a collection
> p = {firstname:"Dave", lastname:"Ho"}
> db.person.save(p)
> db.person.insert({firstname:"Ricky", lastname:"Ho"})

# Show all docs within a collection
> db.person.find()

# Iterate result using cursor
> var c = db.person.find()
> p1 = c.next()
> p2 = c.next()

> p3 = db.person.findone({lastname:"Ho"})

# Return a subset of fields (ie: projection)
> db.person.find({lastname:"Ho"}, {firstname:true})

# Delete some records
> db.person.remove({firstname:"Ricky"})

# To build an index for a collection
> db.person.ensureIndex({firstname:1})

# To show all existing indexes
> db.person.getIndexes()

# To remove an index
> db.person.dropIndex({firstname:1})

# Index can be build on a path of the doc.
> db.person.ensureIndex({"address.city":1})

# A composite key can be used to build index
> db.person.ensureIndex({lastname:1, firstname:1})

var p1 = db.person.findone({lastname:"Ho"})
p1["address"] = "San Jose"
db.person.save(p1)

# Do the same in one command
db.person.update({lastname:"Ho"},
              {$set:{address:"San Jose"}},
              false,
              true)

var account = db.bank.findone({id:1234})
var old_bal = account['balance']
var new_bal = old_bal + fund

# Pre-condition is specified in search criteria
db.bank.findAndModify({id:1234, balance:old_bal},
                   {$set: {balance: new_bal}})

# Check if the prev command successfully
var success =
   db.runCommand({getlasterror:1,j:true})

if (!success) {
 #retry_from_beginning
}

db.book.insert({title:"NOSQL",
             about:["software", "db"]})

db.book.insert({title:"Java programming",
             about:["software", "program"]})

db.book.insert({title:"Mongo",
             about:["db", "technology"]})

db.book.insert({title:"Oracle",
             about:["db", "software"]})

db.book.find()

m = function() {
 for (var i in this.about) {
     emit(this.about[i], this.title)
 }
}

r = function(k, vals) {
 return({topic:k, title:vals})
}

db.book.mapReduce(m, r, {query:{},
               out:{replace:"mroutput"}})

db.mroutput.find()