install mong db in nodejs | tutorials in nodejs

if user sends any data - that data have to store permanently for that purpose we w ill use database

sql databases - oracle, - sql we will use

in nodejs json is the compatible formati  to storing and retrieving

in this we will go for non sql database called mongodb

sql table

non sql - colection

 in colection we wills tor docoment means json

to more secure - we stored json in binary

what is the use of mongodb

it is scalable

mongoose translator between node js and mongodb

instalation of mongodb

npm i mongoose

it will reflect in package.json in dependencies json

taht version reflect in package 

"mongoose": "^6.7.2",

install mongo db in linux

sudo service mongod stop

Remove Packages

sudo apt-get purge mongodb-org*

Remove the folders

sudo rm -r /var/log/mongodb

sudo rm -r /var/lib/mongodb

2 - Reinstall as described on official site, I will just write down the all steps. enter link description here

Import the public key

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 2930ADAE8CAF5059EE73BB4B58712A2291FA4AD5

Create a list file for Ubuntu 16.04

echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.6 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.6.list

update the list

sudo apt-get update

Install the latest package

sudo apt-get install -y mongodb-org

3 - Now it should work, please try below command

sudo service mongod start

and check the status

mongo

above are not working so install again

install mongo db in another 

sudo apt-get install mongodb

sudo service mongodb start

to start mongo shell write below command

mongo

type the command

it will start shell run commnds

show dbs

it will show what the db u have

TO CREATE NEW DB 

USE DBNAME

use newDB

if u type 

db

it will show ur db

if u type

showdbs

it will show already existed db not ur db

because u not created collections;

to delete database

ist swithc to ur database then

use below command

db.dropDatabase()

db

db.createCollection(name,coletion)

db.createCollection(<name>, {capped: <boolean>, 

autoIndexId: <boolean>, size: <number>, max: <number>,

 storageEngine: <document>, validator: <document>, 

validationLevel: <string>, validationAction: <string>, 

indexOptionDefaults: <document>, viewOn: <string>, 

pipeline: <pipeline>, collation: <document>, writeConcern: <document>})

 db.createCollection("employee",{size:524800,max:100,capped:true})
{ "ok" : 1 }

db.collectionnae.insert(document)

document should be in json format

to see the collection of new ly created 

databse

to get whats the tables there

db.employee.find()

db.employee.find().pretty();

use db.employee.find()

it will show the uniquer character with saved data
db.coollectionnane.find()


to display the read in beter use pretty
 db.employee.find().pretty()

show collections command used to get the tables 

use pretyy 





get age of 20 whoc citiy is london
db.employee.find({city:"lonodon"})


get tje salary 15000 less han
or age less tahn 15

write the query
select name,age,city from employee where age<15

db.employee.find({age: {$lt: 15}},{city:1,name:1,age:1});

$lt - lesser than

$gt - greter than

beaturiful way uisng pretty

db.employee.find({age: {$lt: 15}},{city:1,name:1,age:1}).pretty();

till now we seen create of database 

create of table or collection

reed and filter that table

to update colection use

update - for one document

updateMany - for all document

db.employee.update({name:"vivek"},($set:{age:23}))

db.employee.update({age:3},{$set:{age:23}});

it will marched age 3 wth age 23

if we wanna update all matched rows

use updateMany

db.employee.updateMany({age:2},{$set:{age:5}});

write the queries for salary increase by 2 where city is mumbiai

> db.employee.updateMany({city:"mumbai"},{$mul:{salary:1.02}});

$set, $mul

deletion of document in mongodb

db.collection_name.remove(selection logic)

$eq- equal

$set- update

$lt - less tahn

$gt greter than

db.employee.remove({age:{$eq :20}})




$mul multipy

how to delee complete table

db.employee.remove({})

sudo apt-get install mongodb
sudo service mongodb start
mongo
show dbs
db.dropDatabase()

db.createCollection(name,coletion)
db.createCollection("employee",{size:524800,max:100,capped:true})

db.collectionnae.insert(document)

db.employee.find()

db.employee.find().pretty()

db.employee.find({age: {$lt: 15}},{city:1,name:1,age:1}).pretty();

$lt
$gt 
$set


db.employee.update({age:3},{$set:{age:23}});
db.employee.updateMany({age:2},{$set:{age:5}});
db.employee.updateMany({city:"mumbai"},{$mul:{salary:1.02}});


db.employee.remove({age:{$eq :20}})

db.employee.remove({})