MongoDb Basics


MongoDB Basicss

MongoDB is
  •  an open-source document database .
  •  leading No SQL database. 
  •  written in C++.

Basic Commands and Queries


1. MongoDB use DATABASE_NAME is used to create database. 


use DATABASE_NAME


If you want to create a database with name <mydb>, then use DATABASE statement 



>use mydb
switched to db mydb

2.To check your currently selected database, use the command db

>db
mydb

3.If you want to check your databases list, use the command show dbs.

>show dbs
local     0.78125GB
test      0.23012GB

4.The insert() Method

To insert data into MongoDB collection, you need to use MongoDB's insert() or save() method.

>db.COLLECTION_NAME.insert(document)

Insert a single document
    db.collection_name_here.insert({});

Example : - 
db.collection_name_here.insert({
"name" : "your name",
"age" : 22
})

Insert multiple documents at the same time
db.collection_name_here.insert([{},{},{},{}])

Example : -
db.collection_name_here.insert([{"name" : "sanduni", "age" : 23},{"name" : "hiruni", "age" : 23},{"name" : "nimasha", "age" : 27},{"name" : "lochana", "age" : 22}])

Note the syntax difference between inserting a single document and multiple documents

5.The Find method

To query data from MongoDB collection, you need to use MongoDB's find() method.

find() method will display all the documents in a non-structured way.

>db.COLLECTION_NAME.find()


6.The pretty() Method

To display the results in a formatted way, you can use pretty() method.

>db.mycol.find().pretty()

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

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