Aggregation Overview

We are discussing another important concept in MongoDB, that is our aggregation overview

In case of aggregation, aggregation is nothing but one process which will take multiple

data and it will do some computation on the data and the result will be returned

So, now let us go for further discussion on this aggregation overview

So, what is aggregation in MongoDB? Aggregations, operations, process, data records and return the computed results

So multiple data will be taken and complete. results will be returned so aggregation operations group values from

multiple documents together and can perform a variety of operations on the group

data to return a single result as an example we can say some we can say

average we can say max we can say minimum so in this case what is happening we are

taking huge number of data and we are doing some competition and as a result

we are returning a single result and that is no as the aggregation here. So, aggregation operations group values from multiple documents

together. So, you know that this is our MongoDB is our document-oriented database. So

we'll be having the collections which is symbolizing the tables and documents are symbolizing

records. So it will take multiple documents, that means multiple records, and then can perform

a variety of operations on the group data Let it be addition let it be maximum calculations or minimum calculations or average calculations and on return it will return a single result The MongoDB has the method that is the aggregate method

The syntax of this method is db. .collection name, dot aggregate and then aggregate operation

So, db. .collection underscore name, that is a collection name. . aggregate that is an aggregate method and that is a aggregate operation

So, this is the syntax in which we can call this aggregate method to do the aggregation

So, here you can find we're having this dollar sum, we're having dollar AVG, dollar

mean, dollar max, dollar push, dollar first, dollar last. So these are the different expressions are there

So let us discuss the respective descriptions. So dollar sum from the name from this expression, it is quite obvious that what is the

purpose, add the field values of all the documents. Next, dollar average

So, finds the average for all the values of a field. Dollar mean

So, finds the minimum value of a field. Dollar max. So, from the very expression name, we are getting this idea, finds the maximum value

of a field. Dollar push, insert value to an array in the document

We're having dollar first. So get the first document from the collection

Dollar last, so get the last document from the collection. So, in the next video, we'll be going for one example of this aggregation

Please watch that one because that will be associated with some demonstration

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