SQL Oracle /聚合查询

Question

I'm trying to run a query on Oracle. I've a table of settled payments for accounts, I have a query which pulls through the last three settled amounts, plus any amount which was written off, for any account I need this info for.

However, some of the accounts are weekly based, and for these I would like to aggregate their weekly settlements into their monthly groups. Here is the code I have so far:

SELECT   *
FROM     (
    SELECT *
    FROM   (
            SELECT   gwod.account_id,
                     gwod.charge_period_start,
                     SUM(gwod.total_due_on_charge) total_due_on_charge,
                     SUM(gwod.amount_written_off) amount_written_off,
                     DENSE_RANK() over (PARTITION BY gwod.account_id 
                                        ORDER BY charge_period_start DESC) rownumber
            FROM     report.accounts_write_off gwod
            WHERE    account_id IN (‘account_number’)
            GROUP BY gwod.account_id,
                     gwod.charge_period_start
            HAVING   SUM (gwod.total_due_on_charge) <> 0) t1
    WHERE  t1.rownumber <=3) 
    PIVOT (MAX(charge_period_start) charge_period, 
           MAX(total_due_on_charge) total_due_on_charge, 
           MAX(amount_written_off) amount_written_off 
           FOR rownumber IN (1,2,3))
ORDER BY account_id.* 

This works perfectly but for the weekly based accounts, so rather than pulling through the last three weekly amounts which were settled, ie 25-09-17, 18-09-17, 11-09-2017, I'd like to pull through the aggregated payments for September, August, and July.

I hope all this makes sense.

Answer 1

Simply change your aggregation from current unit level (ie, weekly) to month level with EXTRACT(month ...) in inner query's SELECT and GROUP BY as well as PARTITION and PIVOT clauses:

SELECT   *
FROM     (
    SELECT *
    FROM   (
            SELECT   gwod.account_id,
                     EXTRACT(month FROM gwod.charge_period_start) charge_period_month,
                     SUM(gwod.total_due_on_charge) total_due_on_charge,
                     SUM(gwod.amount_written_off) amount_written_off,
                     DENSE_RANK() over (PARTITION BY gwod.account_id 
                                        ORDER BY EXTRACT(month FROM gwod.charge_period_start) DESC) rownumber
            FROM     report.accounts_write_off gwod
            WHERE    account_id IN ('account_number')
            GROUP BY gwod.account_id,
                     EXTRACT(month FROM gwod.charge_period_start)
            HAVING   SUM (gwod.total_due_on_charge) <> 0) t1
    WHERE  t1.rownumber <=3) 
    PIVOT (MAX(charge_period_month) charge_period, 
           MAX(total_due_on_charge) total_due_on_charge, 
           MAX(amount_written_off) amount_written_off 
           FOR rownumber IN (1,2,3))
ORDER BY account_id.* 

DEMO (with random data) :

http://rextester.com/UJK84858