How to apply aggregation function sum() on attribute

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1

I want to sum up all the attribute value. I have tried the following query but it doesn’t work.

for $i in input()/bank/client/account/depositor
return sum({data($i/@amount)})

the output is:
sum(100)
sum(500)
sum(240)

My expected output is 840

Can anyone help me?

2

The result you are getting is because you are summing each resulting document from the ‘for’ so the result is correct. To get a sum of all @amount attributes you need to reformulate the query thus:

let $values := (for $doc in input()/bank return xs:integer($doc/client/account/depositor/@amount))
return xs:integer(sum($values))

This way the sum function operates on a array of integer values and returns an integer result.

Hope this helps.