Sum for flere datointervaller i en enkelt forespørgsel?

Hvis jeg antager, at jeg forstår din anmodning korrekt, tror jeg, at det, du har brug for, er noget i denne retning:

SELECT "periods"."start_date", 
       "periods"."end_date", 
       SUM(CASE WHEN "balance_transactions"."created" BETWEEN "periods"."start_date" AND "periods"."end_date" THEN "balance_transactions"."fee" ELSE 0.00 END) AS period_sum
  FROM "balance_transactions" 
  JOIN charges ON balance_transactions.source = charges.balance_id 
  JOIN ( SELECT '2013-12-20'::date as start_date, '2014-01-19'::date as end_date UNION ALL
         SELECT '2013-12-21'::date as start_date, '2014-01-20'::date as end_date UNION ALL
         SELECT '2013-12-22'::date as start_date, '2014-01-21'::date as end_date UNION ALL
         SELECT '2013-12-23'::date as start_date, '2014-01-22'::date as end_date UNION ALL
         SELECT '2013-12-24'::date as start_date, '2014-01-23'::date as end_date
         ) as periods
    ON "balance_transactions"."created" BETWEEN "periods"."start_date" AND "periods"."end_date"
 WHERE "balance_transactions"."account_id" = 6 
   AND "balance_transactions"."type" = 'charge' 
   AND "charges"."refunded" = false 
   AND "charges"."invoice" IS NOT NULL
 GROUP BY "periods"."start_date", "periods"."end_date"

Dette skulle returnere alle de perioder, du er interesseret i, i et enkelt resultatsæt. Da forespørgslen er 'genereret' med det samme i din frontend, kan du tilføje så mange rækker til punktum-delen, som du vil.

Edit:med nogle forsøg og fejl lykkedes det mig at få det til at fungere [i sqlFiddle][1] og opdaterede syntaksen ovenfor i overensstemmelse hermed.