Introduction of mongoDB

What is MongoDB?

MongoDB is a NoSQL database management system. NoSQL because, in SQL or traditional database management systems are RDBMS, it means in SQL or in a traditional database management system we stored data in the form of table(row and columns) but MongoDB stored the data as a collections and documents. Here documents are key-value pairs. Document is the basic unit of data in MongoDB and collection contains the documents. So we can say that collection is a set of documents. Here we don't have any table. In the position of table we have collections. Because in MongoDB there is not table so we don't have row and columns also. In MongoDB in the position of row and column we have documents and these documents are key:value pairs.

Main Components of MongoDB

_id:
The _id field works like the document’s primary key. While creating a document we should create the _id field. If we don't, then MongoDB will automatically generate the _id field. This filed(_id field) represents a unique value in the MongoDB document.
Document
It is a record of MongoDB. Single document means single records. We can compare each row of a RDBMS system with document.
Collection:
Collection is a group of documents. So we can say that collection contains the documents. We can compare collection with a table of RDBMS system.
Field
It is a name and value pair in a document. We can compare field with column of RDBMS system.

What is RDBMS?

RDBMS stands for relational database management systems. In RDBMS data stored in the from of tables. In the table we have column and row. The intersection of colum and row is called a cell. Here you will get index column. So using index number you can get a particular data or a particular chunk of data. Because here we have index, so we can perform sorting here.