MongoDB Aggregation Sum
Example
How to get the summation of amount? See the below aggregate query.
> db.transactions.aggregate(
[
{
$group : {
_id : '$cr_dr',
count : {$sum : 1}, //counts the number
totalAmount : {$sum : '$amount'} //sums the amount
}
}
]
);
And the result is
{
"_id" : "C",
"count" : 3.0,
"totalAmount" : 120.0
}
{
"_id" : "D",
"count" : 5.0,
"totalAmount" : 410.0
}
Another version that sums amount and fee.
> db.transactions.aggregate(
[
{
$group : {
_id : '$cr_dr',
count : {$sum : 1},
totalAmount : {$sum : { $sum : ['$amount', '$fee']}}
}
}
]
);
And the result is
{
"_id" : "C",
"count" : 3.0,
"totalAmount" : 128.0
}
{
"_id" : "D",
"count" : 5.0,
"totalAmount" : 422.0
}
