learn mongodb in 30 minutes

1. syntax for create database

use database_name

use mydb

if already exists, switched to mydb

if not exists, create new database

2. list all database in MongoDb

show dbs

3. syntax for create collection

db.createCollection("collectionname")

4. list all collection

show collections

5. insert values into collections

db.collection_name.insert({"id":"name"})

6. db.collection_name.find()

find() method will display all the documents

7. db.collection_name.find().pretty()

Above query used for arrange the document easy to read format

8. db.COLLECTIONNAME.findOne()

Apart from the find() method, there is findOne() method, that returns only one document.

Operation	Syntax	Example	RDBMS Equivalent
Equality	{<key>:{$eg;<value>}}	db.mycol.find({"by":"tutorials point"}).pretty()	where by = 'tutorials point'
Less Than	{<key>:{$lt:<value>}}	db.mycol.find({"likes":{$lt:50}}).pretty()	where likes < 50
Less Than Equals	{<key>:{$lte:<value>}}	db.mycol.find({"likes":{$lte:50}}).pretty()	where likes <= 50
Greater Than	{<key>:{$gt:<value>}}	db.mycol.find({"likes":{$gt:50}}).pretty()	where likes > 50
Greater Than Equals	{<key>:{$gte:<value>}}	db.mycol.find({"likes":{$gte:50}}).pretty()	where likes >= 50
Not Equals	{<key>:{$ne:<value>}}	db.mycol.find({"likes":{$ne:50}}).pretty()	where likes != 50
Values in an array	{<key>:{$in:[<value1>, <value2>,……<valueN>]}}	db.mycol.find({"name":{$in:["Raj", "Ram", "Raghu"]}}).pretty()	Where name matches any of the value in :["Raj", "Ram", "Raghu"]
Values not in an array	{<key>:{$nin:<value>}}	db.mycol.find({"name":{$nin:["Ramu", "Raghav"]}}).pretty()	Where name values is not in the array :["Ramu", "Raghav"] or, doesn’t exist at all

If you have any doubts, comment below

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