I have the following query:

```
SELECT 
   SUM("balance_transactions"."fee") AS sum_id 
   FROM "balance_transactions" 
   JOIN charges ON balance_transactions.source = charges.balance_id 
   WHERE "balance_transactions"."account_id" = 6 
      AND (balance_transactions.type = 'charge' 
      AND charges.refunded = false 
      AND charges.invoice IS NOT NULL) 
      AND ("balance_transactions"."created" BETWEEN '2013-12-20' AND '2014-01-19');

```

What that does is adds up all the "fees" that occurred between those two dates. Great. Works fine.

The problem is that I almost always need those fees for hundreds of date ranges at a time, which amounts to me running that same query hundreds of times. Not efficient. 

But is there some way to condense this into a single query for all the date ranges?

For instance, I'd be calling `SUM` for a series of ranges like this:

```
2013-12-20 to 2014-01-19
2013-12-21 to 2014-01-20
2013-12-22 to 2014-01-21
2013-12-23 to 2014-01-22
2013-12-24 to 2014-01-23
...so on and so on

```

I need to output the sum of fees collected in each date range (and ultimately need that in an array).

So, any ideas on a way to handle that and reduce database transactions?

FWIW, this is on Postgres inside a Rails app.