Gain insights into MongoDB's core concepts, including queries, CRUD operations, aggregation, and more. Discover how to build applications with hands-on experience and interactive widgets.

mongo.tar.gz

MongoDB is an open-source NoSQL database and stores data in the form of documents. It can be used as an alternative to traditional relational databases. NoSQL databases are schema-less and useful for working with large sets of distributed data. 

In this course, you will learn the core concepts of MongoDB including queries, documents, embedded documents, and operators with advanced features like CRUD operations, bulk write operations, GridFS, indexing, aggregation pipeline, authorization, and more.

You will have plenty of hands-on experience with the help of interactive widgets, and by the end you will have a strong understanding of how to build MongoDB-based applications.

MongoDB: The Complete Guide

# Projection operators
**Projection** means to select only the necessary data instead of the entire document. The projection operators are used to project the output of the query. The second argument of `find` functions is a projection document, and we can only define projection operators inside it. 

## ` operator
The **`$`** operator is called the positional operator, and it's used to project the first array element from the document. Below are a few points to remember about the positional operator:

1. It is applied only on the `array` field.
2. It works only if the `array` field is included in the filter query, otherwise, it throws an error.
3. It only appears at the end of the field path.

Syntax:

```
{
    '<field-path>.$': 1
}
```
The `<field-path>` can either be a single field or a path for an embedded document field.

First, let’s insert some documents with an `array` field.

## ` operator
The **`＄`** operator is called the positional operator, and it's used to project the first array element from the document. Below are a few points to remember about the positional operator:

1. It is applied only on the `array` field.
2. It works only if the `array` field is included in the filter query, otherwise, it throws an error.
3. It only appears at the end of the field path.

Syntax:

```
{
    '<field-path>.$': 1
}
```
The `<field-path>` can either be a single field or a path for an embedded document field.

First, let’s insert some documents with an `array` field.

Introduction to Database and MongoDB

Create Database and Authorization

Performing CRUD Operations on MongoDB - Part 1

Performing CRUD Operations on MongoDB - Part 2

MongoDB Query and Database Performance

Learn Additional MongoDB Topics

Appendix

Read Documents: Part 6

Projection operators

`$` operator

Read Documents: Part 6

Projection operators

$ operator

`$` operator