Data Types

• String: Refers to plain text

• Number: Consists of all numeric fields

• Boolean: Consists of True or False

• Object: Other embedded JSON objects

• Array: Collection of fields

• Null: Special value to denote fields without any value

{audience_rating: 6}
{audience_rating: 7.6}

{"title": "A Swedish Love Story", released: "1970-04-24"}
{"title": "A Swedish Love Story", released: "24-04-1970"}
{"title": "A Swedish Love Story", released: "24th April 1970"}
{"title": "A Swedish Love Story", released: "Fri, 24 Apr 1970"}

Variables

var name="Rachel Green"
name

var plainNum = 1299

plainNum

// forces MongoDB to use 32 bit
var explicitInt = NumberInt("1299")

explicitInt

// long forces 64 bit

var explicitLong = NumberLong("777888222116643")

explicitLong

var explicitLong_double = NumberLong(444333222111242)

explicitLong_double

// forces 128 bit

var explicitDecimal = NumberDecimal("142.42")

explicitDecimal

var explicitDecimal_double = NumberDecimal(142.42)

explicitDecimal_double

//values are rounded off
var decDbl = NumberDecimal(5999999999.99999999)

decDbl

// boolean demo

var isActive=true

isActive

var isDeleted=false

isDeleted

// objects

var friend={
    "first_name":"Rachel",
    "last_name":"Green",
    "email":"[e-mail]"
}

friend

friend.first_name


var friends1=[
{
    "firstname": "Phoebe",
    "lastname":"Buffay",
    "age": 31,
    "profession":"Therapist"
},
{
    "firstname": "Ross", 
    "lastname":"Geller",
    "age": 31,
    "location": "NY",
    "profession":"Palentologist",
    "spouses":["Carol","Emily","Rachel"]
},
{
    "firstname": "Chandler",
    "lastname":"Bing",
    "age": 31,
    "location": "NY"
},
{
    "firstname": "Joey",
    "lastname":" Tribianni",
    "age": 32,
    "location": "NYC",
    "profession":"actor"
}
]


var friends2 = [
{
    "firstname": "rachel",
    "lastname" : "green",
    "age" : 30,
    "location": "NYC",
    "profession":"Fashion Designer"
},
{
    "name":{"firstname":"Ben",
            "lastname" : "Geller"}, 
    "age" : 6,
    "location": "NYC"
},
{
    "name":{"firstname":"Emma",
            "lastname" : "Geller"},
    "age" : 1,
    "location": "NYC"
}
]

Skip - Limit

db.friendsCollection.find().sort({"lastname":1,"firstname":1}).limit(2)

db.friendsCollection.find().sort({"lastname":1,"firstname":1}).skip(2).limit(2)

Sort

db.friendsCollection.drop()

db.friendsCollection.insertMany(friends1)
db.friendsCollection.insertMany(friends2)

db.friendsCollection.find().sort({"firstname":1})
db.friendsCollection.find().sort({"firstname":-1})

Projection

MongoDB projections specify which fields should be returned in the documents that match a query. All fields are returned by default, but you can include or exclude specific fields to control the amount of data MongoDB returns.

Projections can help improve performance by reducing network bandwidth and processing time, especially for documents with large amounts of data or when you only need a subset.

Return firstname and lastname only

This query tells MongoDB to return only the firstname and profession fields of all documents in the friends1 collection. If you want to exclude the _id field as well, you can do so by explicitly setting it to 0 in the projection:

db.friendsCollection.find({},{"firstname":1,"lastname":1})

db.friendsCollection.find({},{"_id":0,"firstname":1,"lastname":1})

// Exclude Location

db.friendsCollection.find({ firstname: "Joey" }, { location: 0 })


db.friendsCollection.find({}, { "name.firstname": 1, age: 1 })

Distinct Count

db.friendsCollection.distinct("lastname")

db.friendsCollection.distinct("lastname",{"email":{$regex:".*friends"}})

db.friendsCollection.count()
// without condition, this will check the metadata and return the count. 
// It will not be accurate all the time due to multi-node architecture 
// and the time taken to sync.

db.friendsCollection.count({"lastname":"Geller"})


// newer syntaxes always query need to be passed, it’s slower

db.friendsCollection.countDocuments({"lastname":"Geller"})

// newer syntaxes to get an overall idea using metadata, quick result

db.friendsCollection.estimatedDocumentCount({"lastname":"Geller"})

Array Slice

db.friendsCollection.find({"firstname":{$eq:"Ross"}}, {"spouses":{$slice:1}})

db.friendsCollection.find({"firstname":{$eq:"Ross"}}, {"spouses":{$slice:-1}})