Question

I have following properties in my current Account Balance object:

long id;                     // Database ID
Date date;                   // date when this balance object was created
boolean currentBalanceFlag;  // indicates this is the most recent balance
float amount;                // the total sum currently in the account balance
float depositAmount;         // amount deposited that resulted in this objects amount 
float withdrawalAmount;      // amount withdrawn that resulted in this objects amount
Balance lastBalance;         // last balance object for traversing
User user;                   // owner of the balance
String note;                 // detailed description of transaction that resulted in current blanace

There are only two actions performed on the balance. Deposits and withdrawals.

The question is:

How do I create HQL query that will:

-sum all the depositAmount for user
-sum all withdrawalAmount for user
-subtract result of the first summation from second summation
-compare result of subtraction with the amount for user in Balance object that has currentBalanceFlag equal to true

in pseudo code:

resultAmount = select ( sum(depositAmount) - sum(withdrawalAmount) ) from Balance where user=user
amount = select amount from Balance where user=user and currentBalanceFlag=true

And the final boolean result I’d like to get from single call to the database with HQL query:

resultAmount == amount

Answer 1

select (sum(flow.depositAmount) - sum(flow.withdrawalAmount) - current.amount) 
from Balance flow, Balance current
where flow.user=:user
and current.user=:user 
and current.currentBalanceFlag=true

This will return the difference between the sum of all flows and the current balance.

On a side note, you shouldn’t have to check the integrity of your data. Unless you have gazillions of lines, computing the current balance with an SQL sum should be fast enough.