Mongodb java aggregate sum example
I am trying to perform a mongodb aggregation using Java and unable to figure out how to sum 2 fields individually. Below is my document structure: Show
I am trying to sum using:
I also tried:
When I run this aggregation, the result of defective is always NULL. I want the result as:
Is the above possible or should I perform 2 separate aggregations? Docs Home → MongoDB Manual $sum Changed in version 5.0. Calculates and returns the collective sum of numeric values.
In MongoDB 3.2 and earlier, When used in the When used in
other supported stages,
For more information on expressions, see Expressions. The result will have the same type as the input except when it cannot be represented accurately in that type. In these cases:
If used on a field that contains
both numeric and non-numeric values, If used on a field that does not exist in any document in the collection, If all operands are non-numeric, In the In the other supported stages:
Consider a
Grouping the documents by the day and the year of the
The operation returns the following results:
Using
The operation returns:
The
TipSee also:A collection
The following example uses the
The operation results in the following documents:
New in version 5.0. Create a
This example uses
In the example:
In this output, the sum of the
How aggregate is used in MongoDB in Java?In this guide, you can learn how to use aggregation operations in the MongoDB Java driver. Aggregation operations process data in your MongoDB collections and return computed results.. select what documents to return.. select what fields to return.. sort the results.. How do I sum fields in MongoDB?If used on a field that contains both numeric and non-numeric values, $sum ignores the non-numeric values and returns the sum of the numeric values. If used on a field that does not exist in any document in the collection, $sum returns 0 for that field. If all operands are non-numeric, $sum returns 0 .
How do I count aggregates in MongoDB?MongoDB $count Aggregation
The MongoDB $count operator allows us to pass a document to the next phase of the aggregation pipeline that contains a count of the documents. There a couple of important things to note about this syntax: First, we invoke the $count operator and then specify the string.
How does MongoDB calculate sum of salary?$sum operator returns the sum of all numeric values of documents in the collection in MongoDB. Above will create collection (or table) (if collection already exists it will insert documents in it). Step 2.1 - We will group employee by firstName and find sum of salary of each group.
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