Learn MongoDB Step By Step

Wow, we have created a database and also we have dropped it.

Note

Create demodatabase Database if you have drop demodatabase for further demos.

Insert Document

Basic understanding if you know SQL [Document == Row and Collection== Tables] in MongoDB.

Inserting Document in MongoDB Collection as we insert row in SQL server table

In this part, we are simply going to insert Name and Profession of the employee.

Definition

See List of Insert Document

In Mongo DB if you want to see all list of document in particular collection then you need to enter command

“db.[Collection Name].find()”

In this part, we are simply going to see a list of employees which we have inserted.

Definition

Note

What is an employee? Answer: - it is a collection which we have created.

Search Document by field (column)

In Mongo DB if you want to search a single document in particular collection then we can use findOne Method.

In this part, we are simply going to search employee by name, and for doing that we need specific selection criteria in findOne Method.

Definition

Delete Document

Using DeleteOne Method (To Delete Single Document)

Delete at most a single document that matches a specified filter even though multiple documents may match the specified filter.

In this part, we are going to delete employee document using deleteOne Method, for deleting document we also need to specify a filter and if the filter gets more than one record then the first document that matches the filter will be deleted.

Note

Deletes the first document that matches the filter.

Using remove Method (To Delete Single Document)

Delete a single document or all documents that match a specified filter.

If we want to remove single document then we need to use particular id (Objectid which is a unique id in MongoDB) or another unique field.

We are going to use Objectid (Objectid is unique id) for deleting a particular employee document.

Using remove Method for Deleting document using Unique Field other than Objectid

Delete document using remove method but this time we are going to use another unique field (“Name”) for removing the document.

Deleting all Document

1. Using Remove Method(for removing all documents)
   For Deleting all documents we do not need to pass any filter just pass empty document ({ }) as shown in below syntax.
   
   
   
   We just need to pass Collection name and then remove method with empty document ({ }).
   
   

2. Using Deleting Many Method
   Removes all documents that match the filter from a collection
   
   In this part we are going to delete employee based on Profession, we have 3 employees of student professions which we are going to delete.
   
   
   

Updating Document

Updates an existing document or documents in a collection, by default update document, update the only single document.

For updating documents we first need to pass the selection criteria for the update (means a unique id or field on which we can select fields to update) then after that, we need to pass data to update (document).

In this part we are going to update employee details based on Object id which we are going to pass in selection criteria then in the $set we are going to update employee Profession from “PL SQL Developer” to “Node.js Developer”.

Note

1. The $set operator replaces the value of a field with the specified value.
2. To update multiple documents set the Multi parameter to true by default it is false in options
   
   

Using updateOne Method (To update only single document)

Updates a single document within the collection based on the filter.

For updating document we first need to pass the selection criteria for the update (means a unique id or field on which we can select fields to update) then after that, we need to pass data to update (document).

In this part we are going to update employee details based on Object id which we are going to pass in selection criteria then in the $set we are going to update employee Profession from “Developer” to “C# Developer”.

Note

Options are Optional.

Using updateMany Method (To update only single document)

Updates multiple documents within the collection based on the filter.

For updating document we first need to pass the selection criteria for the update (means a unique id or field on which we can select fields to update) then after that, we need to pass data to update (document).

In this part we are going to update employee details based on Profession which we are going to pass in selection criteria then in the $set we are going to update employee Salary to “60000”.

Using Count () Method

Count Number of Document in Collection

Using Collection.count() method we can count a number of the document in particular collection.

In this part, we are going to count a number of employees in collections.

Using count () Method with query selection criteria

Using count () method with selection criteria we can count a number of the document in particular collection which is returned according to criteria.

In this part, we are going to count a number of employees whose Name equals “Sai” (criteria) in collections.

Using Distinct Method

Finds the distinct values for a specified field across a single collection and returns the results in an array.

In this part, we are going use distinct method for getting distinct employees name from collections.

Reference from

https://docs.mongodb.com

In this article, we have learned how to set up MongoDB server and how to use basics Commands of MongoDB.