Mongo DB - NoSQL
What is Mongo DB
MongoDB is an open-source document database and leading NoSQL database. MongoDB is written in C++.
MongoDB is a cross-platform, document-oriented database that provides, high performance, high availability, and easy scalability. MongoDB works on the concept of collection and document.
Database
The database is a physical container for collections
Collection
A collection is a group of MongoDB documents. It is the equivalent of an RDBMS table
Document
A document is a set of key-value pairs. Documents have a dynamic schema. Documents in the same collection do not need to have the same set of fields or structure, and common fields in a collection's documents may hold different types of data.
_id Field of a Document
_id is a 12 bytes hexadecimal number which assures the uniqueness of every document. You can provide _id while inserting the document. If you don’t provide then MongoDB provides a unique id for every document.
These 12 bytes are divided:
first 4 bytes for the current timestamp, next 3 bytes for machine id, next 2 bytes for process id of MongoDB server and remaining 3 bytes are simple incremental VALUE.
Create DB
use DATABASE_NAME
The command will create a new database if it doesn't exist, otherwise, it will return the existing database.
Drop Database
db.dropDatabase()
To drop an existing database
Create Collection
db.createCollection(name, options)
Used to create a collection
Drop Collection
db.COLLECTION_NAME.drop()
Insert a Document
db.collection1.insert({
_id: ObjectId(12345abceert),
title: 'MongoDB sample,
description: 'No SQL db MongoDB ',
by: 'tech trends',
tags: ['mongodb', 'database', 'NoSQL'],
likes: 200
})
Here collection1 is the collection nameIf the collection doesn't exist in the database, then MongoDB will create this collection and then insert a document into it.
The find() Method
You need to use MongoDB's find() method to query data from MongoDB collection,
db.COLLECTION_NAME.find()
AND in MongoDB
Following example will show all the books written by 'John Kelvin' and whose title is 'MongoDB sample'.
>db.collection1.find({$and:[{"by":"John Kelvin"},{"title": "MongoDB Overview"}]}).pretty() {
"_id": ObjectId(1wf78ad8902c),
"title": "MongoDB sample",
"description": "MongoDB is no sql database",
"by": "John Kelvin",
"tags": ["mongodb", "database", "NoSQL"],
"likes": "200"
}
OR in MongoDB
Following example will show all the tutorials written by 'John Kelvin' or whose title is 'MongoDB sample'.
>db.collection1.find({$or:[{"by":"John Kelvin"},{"title": "MongoDB Overview"}]}).pretty()
{
"_id": ObjectId(1wf78ad8902c),
"title": "MongoDB sample",
"description": "MongoDB is no sql database",
"by": "John Kelvin",
"tags": ["mongodb", "database", "NoSQL"],
"likes": "200"
}
MongoDB is a cross-platform, document-oriented database that provides, high performance, high availability, and easy scalability. MongoDB works on the concept of collection and document.
Database
The database is a physical container for collections
Collection
A collection is a group of MongoDB documents. It is the equivalent of an RDBMS table
Document
A document is a set of key-value pairs. Documents have a dynamic schema. Documents in the same collection do not need to have the same set of fields or structure, and common fields in a collection's documents may hold different types of data.
_id Field of a Document
_id is a 12 bytes hexadecimal number which assures the uniqueness of every document. You can provide _id while inserting the document. If you don’t provide then MongoDB provides a unique id for every document.
These 12 bytes are divided:
first 4 bytes for the current timestamp, next 3 bytes for machine id, next 2 bytes for process id of MongoDB server and remaining 3 bytes are simple incremental VALUE.
Create DB
use DATABASE_NAME
The command will create a new database if it doesn't exist, otherwise, it will return the existing database.
Drop Database
db.dropDatabase()
To drop an existing database
db.createCollection(name, options)
Used to create a collection
Drop Collection
db.COLLECTION_NAME.drop()
Used to drop a collection
Insert a Document
db.collection1.insert({
_id: ObjectId(12345abceert),
title: 'MongoDB sample,
description: 'No SQL db MongoDB ',
by: 'tech trends',
tags: ['mongodb', 'database', 'NoSQL'],
likes: 200
})
Here collection1 is the collection nameIf the collection doesn't exist in the database, then MongoDB will create this collection and then insert a document into it.
The find() Method
You need to use MongoDB's find() method to query data from MongoDB collection,
db.COLLECTION_NAME.find()
AND in MongoDB
Following example will show all the books written by 'John Kelvin' and whose title is 'MongoDB sample'.
>db.collection1.find({$and:[{"by":"John Kelvin"},{"title": "MongoDB Overview"}]}).pretty() {
"_id": ObjectId(1wf78ad8902c),
"title": "MongoDB sample",
"description": "MongoDB is no sql database",
"by": "John Kelvin",
"tags": ["mongodb", "database", "NoSQL"],
"likes": "200"
}
OR in MongoDB
Following example will show all the tutorials written by 'John Kelvin' or whose title is 'MongoDB sample'.
>db.collection1.find({$or:[{"by":"John Kelvin"},{"title": "MongoDB Overview"}]}).pretty()
{
"_id": ObjectId(1wf78ad8902c),
"title": "MongoDB sample",
"description": "MongoDB is no sql database",
"by": "John Kelvin",
"tags": ["mongodb", "database", "NoSQL"],
"likes": "200"
}
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