Get the sales count within a month - oracle

Question

I have monthly agents' sales data. I need to get the first 25 days sales count and last 5 days columns.
How to get in separately.
I have below table
Agent_ID Date Device
2343 1/1/2019 33330
3245 1/1/2019 43554
2343 5/1/2019 46665
3245 10/1/2019 78900
2343 15/1/2019 55678
2343 26/1/2019 45678
3245 28/1/2019 48900
2343 30/1/2019 56710
5645 12/1/2019 33067
5645 15/1/2019 44890
2121 31/1/2019 55810
I need to get this below output table
Agent_ID first_25days_sale_count Last_5days_sale_count
2343 3 2
3245 2 1
5645 2 0
2121 0 1

Answer 1

Some months have 28, 29 or 31 days so naively using "first 25 days" and "last 5 days" may lead to either double counting (i.e. days 24 and 25 when February has 28 days) or not counting some days (i.e. day 26 when the the month has 31 days). You should decide whether you want to count:
The first 25 days and then the remaining 3-6 days after that; or
The last 5 days and then the 23-26 days before that.
Whichever you chose, you can use conditional aggregation:
SELECT agent_id,
COUNT(
CASE
WHEN EXTRACT( DAY FROM "Date" ) <= 25
THEN 1
END
) AS first_25days_sale_count,
COUNT(
CASE
WHEN EXTRACT( DAY FROM "Date" ) > 25
THEN 1
END
) AS after_first_25days_sale_count,
COUNT(
CASE
WHEN "Date" < TRUNC( LAST_DAY( "Date" ) ) - INTERVAL '4' DAY
THEN 1
END
) AS not_last_5days_sale_count,
COUNT(
CASE
WHEN "Date" >= TRUNC( LAST_DAY( "Date" ) ) - INTERVAL '4' DAY
THEN 1
END
) AS last_5days_sale_count
FROM your_table
GROUP BY agent_id;
So, for your sample data:
CREATE TABLE your_table ( Agent_ID, "Date", Device ) AS
SELECT 2343, DATE '2019-01-01', 33330 FROM DUAL UNION ALL
SELECT 3245, DATE '2019-01-01', 43554 FROM DUAL UNION ALL
SELECT 2343, DATE '2019-01-05', 46665 FROM DUAL UNION ALL
SELECT 3245, DATE '2019-01-10', 78900 FROM DUAL UNION ALL
SELECT 2343, DATE '2019-01-15', 55678 FROM DUAL UNION ALL
SELECT 2343, DATE '2019-01-26', 45678 FROM DUAL UNION ALL
SELECT 3245, DATE '2019-01-29', 48900 FROM DUAL UNION ALL
SELECT 2343, DATE '2019-01-30', 56710 FROM DUAL UNION ALL
SELECT 5645, DATE '2019-01-12', 33067 FROM DUAL UNION ALL
SELECT 5645, DATE '2019-01-15', 44890 FROM DUAL UNION ALL
SELECT 2121, DATE '2019-01-31', 55810 FROM DUAL;
This outputs:
AGENT_ID | FIRST_25DAYS_SALE_COUNT | AFTER_FIRST_25DAYS_SALE_COUNT | NOT_LAST_5DAYS_SALE_COUNT | LAST_5DAYS_SALE_COUNT
-------: | ----------------------: | ----------------------------: | ------------------------: | --------------------:
3245 | 2 | 1 | 2 | 1
2121 | 0 | 1 | 0 | 1
5645 | 2 | 0 | 2 | 0
2343 | 3 | 2 | 4 | 1
db<>fiddle here