Defining, Creating and Dropping a MongoDB collection

MongoDB, the most popular NoSQL database, is an open-source document-oriented database. The term ‘NoSQL’ means ‘non-relational’. It means that MongoDB isn’t based on the table-like relational database structure but provides an altogether different mechanism for storage and retrieval of data.

It is the basic unit of MongoDB and a single record inside a collection is known as a document. It is a JSON object which has the data in the form of key-value pairs.

It is the grouping of documents. A collection belongs to a single database inside MongoDB. The collection the contains the data in the form of document just like the table of RDBMS which contains the data in the form of rows and columns.

As a collection belongs to a single database so first we will have to create a database for creating a collection

STEP 1: First run the following command into your mongo shell or command prompt

mongo

STEP 2: Check all the existing databases by using the following command

show dbs

STEP 3: Creating a database Here we are creating a database named as- w3wiki

use w3wiki

If the database w3wiki is present it will switch to it, else it will create a new database name as w3wiki and then switch to it as shown below.

STEP 4: Create a Collection

Collection is created using createCollection() method.Collection name is passed as argument in the method.

Syntax:

db.createCollection(‘Collection_name’);

Example : Create Student Collection

Query:

db.createCollection(‘Student’);

Inserting only one document at a time

db.collection.insertOne(document)

Inserting more than one document at a time

db.collection.insertMany([,document_1, document_2.....,]),

db.collection.update(query, update)
query: An object for finding the document
Example: {"name":"shilpi"}
update: An object for updating the document with set command
Example: {$set:{"age":"23"}}

To edit a mongodb collection update function is used

Apply the query for finding the document which you want to update. In our collection we want to update collection having name as shilpi so query is:

{"name":"shilpi"}

Using the set command to modify the Field Name

Choose which Field Name you want to modify and then enter the new value accordingly into the query. In our collection we want to edit age value to 23 for name shilpi:

{$set:{"age":"23"}}

db.collection.drop()

It will return true if collection is deleted successfully.