List all days between two dates in Oracle - oracle

Question

I am converting a postgres app to an Oracle app.
I came across this query:
WITH cost AS (SELECT
well_schedules.id,
generate_series(well_schedules.start_date::timestamp, well_schedules.end_date, '1 Day') AS "Date",
(well_schedules.drilling_engineering_estimate * well_schedules.well_estimated_working_interest)/((well_schedules.end_date - well_schedules.start_date) + 1) AS "Cost Per Day"
FROM
well_schedules
)
SELECT date_trunc('quarter', "Date"), COUNT("Cost Per Day"), id
FROM cost
GROUP BY id, date_trunc('quarter', "Date")
ORDER BY date_trunc('quarter', "Date")
The part I am struggling with is the generate_series line.
That line takes a start_date and end_date and lists all days between those two dates. We need that information to compile per day/week/month/quarter/year reports (or at least we assume we need that info).
Our data looks like this:
well_schedules
| id | start_date | end_date | cost |
| 1 | '2015-01-01' | '2015-03-20' | 100 |
We assume cost_per_day is equal across all days, so we'd like to generate a report that lets us look at cost_per_day, cost_per_week, cost_per_month, cost_per_year, and cost_per_quarter. cost_per_week/month/quarter/year is calculated by grouping the days by week/month/quarter/year and summing the associated cost_per_days

Answer 1

SQL Fiddle
Oracle 11g R2 Schema Setup:
CREATE TABLE well_schedules ( id, start_date, end_date, cost ) AS
SELECT 1 , DATE '2015-01-01', DATE '2015-01-20', 100 FROM DUAL;
Query 1:
SELECT ID,
COLUMN_VALUE AS Day,
COST / ( end_date - start_date + 1 ) AS Cost_per_day
FROM well_schedules,
TABLE (
CAST(
MULTISET(
SELECT start_date + LEVEL - 1
FROM DUAL
CONNECT BY start_date + LEVEL - 1 <= end_date
)
AS SYS.ODCIDATELIST
)
)
Results:
| ID | DAY | COST_PER_DAY |
|----|---------------------------|--------------|
| 1 | January, 01 2015 00:00:00 | 5 |
| 1 | January, 02 2015 00:00:00 | 5 |
| 1 | January, 03 2015 00:00:00 | 5 |
| 1 | January, 04 2015 00:00:00 | 5 |
| 1 | January, 05 2015 00:00:00 | 5 |
| 1 | January, 06 2015 00:00:00 | 5 |
| 1 | January, 07 2015 00:00:00 | 5 |
| 1 | January, 08 2015 00:00:00 | 5 |
| 1 | January, 09 2015 00:00:00 | 5 |
| 1 | January, 10 2015 00:00:00 | 5 |
| 1 | January, 11 2015 00:00:00 | 5 |
| 1 | January, 12 2015 00:00:00 | 5 |
| 1 | January, 13 2015 00:00:00 | 5 |
| 1 | January, 14 2015 00:00:00 | 5 |
| 1 | January, 15 2015 00:00:00 | 5 |
| 1 | January, 16 2015 00:00:00 | 5 |
| 1 | January, 17 2015 00:00:00 | 5 |
| 1 | January, 18 2015 00:00:00 | 5 |
| 1 | January, 19 2015 00:00:00 | 5 |
| 1 | January, 20 2015 00:00:00 | 5 |

Answer 2

I will suggest the code below that consider the first and last day of the month from two dates:
Example:
Date Initial: 01/10/2014
Date Final: 12/21/2018
The code will return:
01/01/2014
02/01/2014
03/01/2014
04/01/2014
...
12/28/2018
12/29/2018
12/30/2018
12/31/2018
The Code:
SELECT
CAL.DT AS "Date"
,TO_NUMBER(TO_CHAR(CAL.DT,'DD')) AS "Day"
,TO_NUMBER(TO_CHAR(CAL.DT,'MM')) AS "Month"
,TO_NUMBER(TO_CHAR(CAL.DT,'YY')) AS "YearYY"
,TO_NUMBER(TO_CHAR(CAL.DT,'YYYY')) AS "YearYYYY"
,TO_CHAR(CAL.DT,'day') AS "Description_Day"
,TO_CHAR(CAL.DT,'dy') AS "Description_Day_Abrev"
,TO_CHAR(CAL.DT,'Month') AS "Description_Month"
,TO_CHAR(CAL.DT,'Mon') AS "Description_Month_Abrev"
,TO_CHAR(CAL.DT,'dd month yyyy') AS "Date_Text"
FROM (
SELECT
(
TO_DATE(SEQ.MM || SEQ.YYYY, 'MM/YYYY')-1
) + SEQ.NUM AS "DT"
FROM
(
SELECT RESULT NUM,
TO_CHAR(( -- Minimum Date
TO_DATE('01/01/2014', 'DD/MM/YYYY')
) , 'MM') AS "MM",
TO_CHAR(( -- Minimum Date
TO_DATE('01/01/2014', 'DD/MM/YYYY')
) , 'YYYY') AS "YYYY"
FROM
(
SELECT ROWNUM RESULT FROM DUAL CONNECT BY LEVEL <= (
(
-- Maximum Date
LAST_DAY(TO_DATE('31/12/2018', 'DD/MM/YYYY')) -- Always Last Day
-
-- Maximum Date
TRUNC(TO_DATE('01/01/2014', 'DD/MM/YYYY')) -- Always First Day of Month
) + 1 -- Because the First Day (RESULT) don't begin at zero
)
) -- How many sequences (RESULT) to generate
) SEQ
) CAL
;