mongodbHow to aggregate in MongoDB?
MongoDB provides several ways to aggregate data from collections. The most common way is to use the aggregate()
method. This method takes an array of pipeline stages as its argument and returns the aggregated result.
Example
db.collection.aggregate([
{
$group: {
_id: "$department",
totalSalary: { $sum: "$salary" }
}
}
])
Output example
{ "_id" : "IT", "totalSalary" : 15000 }
{ "_id" : "HR", "totalSalary" : 12000 }
Code explanation
aggregate()
: The method used to aggregate data from collections.$group
: The operator used to group documents by a specified field and perform an aggregation on them._id
: The field used to specify the field to group by.$sum
: The operator used to sum the values of a specified field.
Helpful links
More of Mongodb
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- How to update an array element in MongoDB?
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- How to check if array is empty in MongoDB?
- How to empty an array in MongoDB?
- How to update one document in MongoDB?
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