Oracle SQL count days in week for every month

Question

I have these two tables (times and sales):

times

TIME_ID   |   DAY_NAME  |  DAY_NUMBER_IN_WEEK    |  CALENDAR_MONTH_NAME |  CALENDAR_MONTH_ID
1998-01-10|   Monday    |  1                     |  January             |  1684
1998-01-10|   Tuesday   |  2                     |  January             |  1684
1998-01-10|   Wednesday |  3                     |  January             |  1684
...
1998-01-11|   Monday    |  1                     |  February            |  1685
1998-01-11|   Tuesday   |  2                     |  January             |  1685
1998-01-11|   Wednesday |  3                     |  January             |  1685

sales

PROD_ID   |  TIME_ID     |  AMOUNT_SOLD
13        |  1998-01-10  |  1232          
13        |  1998-01-11  |  1233 
14        |  1998-01-11  |  1233

I need to make columns for every day in week (Monday, Tuesday, Wednesday...) and SUM of AMOUNT_SOLD for each PROD_ID for each day for each month.

SELECT SUM(times.day_number_in_week), times.calendar_month_name, times.day_name, times.calendar_year
FROM sales
INNER JOIN times  ON times.time_id = sales.time_id
GROUP BY times.calendar_month_number, times.calendar_month_name, times.day_name, times.calendar_year

Output:

5988    March   Wednesday   1998
9408    April   Thursday    1998
7532    June    Sunday  1998
9220    July    Thursday    1998
7490    July    Sunday  1998
12540   August  Saturday    1998

but this sum all Wednesdays for all years, i need sum of amount for 1 month for all days (Wednesday, Monday...) for one month.

Can you help me?

Answer 1

You can do conditional aggregation:

SELECT 
    t.calendar_year
    t.calendar_month_name, 
    SUM(case when t.day_number_in_week = 1 then s.amount_sold else 0 end) amount_sold_mon,
    SUM(case when t.day_number_in_week = 2 then s.amount_sold else 0 end) amount_sold_tue,
    SUM(case when t.day_number_in_week = 3 then s.amount_sold else 0 end) amount_sold_wed,
    ...
FROM sales s
INNER JOIN times t ON t.time_id = sales.time_id
GROUP BY t.calendar_year, t.calendar_month_number, t.calendar_month_name