MongoDB for dummies

MongoDB WTF?????

• Most important word NOSQL.
• This doesn't mean as the same, it means that not only SQL.
• Distribution , Horizontal scalability and Easy replication is prominent when comes to NOSQL.
• NOSQL databases helped for the rise of Big data, Machine Learning technologies.

•  MongoDB records are called documents.
•  Each MongoDB database (You can have many.) includes collections, which are a set of JSON documents.
•  Each collection and document has an ObjectID created by MongoDB or supplied by the programmer.
• For SQLees or "SQL people",
• Table is like a collection
• Row/Record is like a document
• No keys PK,FK

• For installation refer this

• Create a database

use Products
switched to db Products

• Create a collection

db.createCollection("users")

• Insert an item

db.users.insert([

{

    name:"John",

    email:"john@gmail.com"

}

])

Here the items are added in object form. To many more than one item an array can be used.

• To Select results from db use,

• db.getCollection('users').find({})

/* 1 */

{

    "_id" : ObjectId("5ae6b03fd26140c6db274889"),

    "name" : "bandula",

    "email" : "asdsa@gmail.com"

}

/* 2 */

{

    "_id" : ObjectId("5ae6b099d26140c6db274892"),

    "name" : "John",

    "email" : "john@gmail.com"

}

• For querying parameter can be passed as objects

• db.getCollection('users').find({name:"bandula"})

/* 1 */

{

    "_id" : ObjectId("5ae6b03fd26140c6db274889"),

    "name" : "bandula",

    "email" : "asdsa@gmail.com"

}

• Remove a document 
• db.getCollection('users').remove({name:"john"})

condition to be checked for the removal is passed as object

• Update a document
• db.getCollection('users').updateOne({name:"bandula"},{$set:{email:"bandula@hotmail.com"}})

condition to be checked, updating parameters are passed. updating parameters are passed in the $set object