How to count ratio hourly? - sql

Question

I`m stuck a bit with understanding of my further actions while performing queries.
I have two tables "A"(date, response, b_id) and "B"(id, country). I need to count hourly ratio of a number of entries where response exists to the total number of entries on a specific date. The final selection should consist of columns "hour", "ratio".
SELECT COUNT(*) FROM A WHERE RESPONSE IS NOT NULL//counting entries with response
SELECT COUNT(*) FROM A//counting total number of entries
How to count the ratio? Should I create a separate variable for it?
How to count for each hour on a day? Should I make smth like a loop? + How can I get the "hour" part of a date?
What is the best way to select the hours and counted ratio? Should I make a separate table for it?
I`m rather new to make complex queries, so I woud be happy for every kind of help

Answer 1

You can do this as:
select to_char(datecol, 'HH24') as hour,
count(response) as has_response, count(*) as total,
count(response) / count(*) as ratio
from a
where datecol >= date '2018-09-18' and datecol < date '2018-09-19'
group by to_char(datecol, 'HH24');
You can also do this using avg() -- which is also fun:
select to_char(datecol, 'HH24'),
avg(case when response is not null then 1.0 else 0 end) as ratio
from a
where datecol >= date '2018-09-18' and datecol < date '2018-09-19'
group by to_char(datecol, 'HH24')
In this case, that requires more typing, though.

Answer 2

SQL Fiddle
Oracle 11g R2 Schema Setup:
CREATE TABLE A ( dt, response, b_id ) AS
SELECT DATE '2018-09-18' + INTERVAL '00:00' HOUR TO MINUTE, NULL, 1 FROM DUAL UNION ALL
SELECT DATE '2018-09-18' + INTERVAL '00:10' HOUR TO MINUTE, 'A', 1 FROM DUAL UNION ALL
SELECT DATE '2018-09-18' + INTERVAL '00:20' HOUR TO MINUTE, 'B', 1 FROM DUAL UNION ALL
SELECT DATE '2018-09-18' + INTERVAL '01:00' HOUR TO MINUTE, 'C', 1 FROM DUAL UNION ALL
SELECT DATE '2018-09-18' + INTERVAL '01:10' HOUR TO MINUTE, 'D', 1 FROM DUAL UNION ALL
SELECT DATE '2018-09-18' + INTERVAL '02:00' HOUR TO MINUTE, NULL, 1 FROM DUAL UNION ALL
SELECT DATE '2018-09-18' + INTERVAL '03:00' HOUR TO MINUTE, 'E', 1 FROM DUAL UNION ALL
SELECT DATE '2018-09-18' + INTERVAL '05:10' HOUR TO MINUTE, 'F', 1 FROM DUAL;
Query 1:
SELECT b_id,
TO_CHAR( TRUNC( dt, 'HH' ), 'YYYY-MM-DD HH24:MI:SS' ) AS hour,
COUNT(RESPONSE) AS total_response_per_hour,
COUNT(*) AS total_per_hour,
total_response_per_day,
total_per_day,
COUNT(response) / total_response_per_day AS ratio_for_responses,
COUNT(*) / total_per_day AS ratio
FROM (
SELECT A.*,
COUNT(RESPONSE) OVER ( PARTITION BY b_id, TRUNC( dt ) ) AS total_response_per_day,
COUNT(*) OVER ( PARTITION BY b_id, TRUNC( dt ) ) AS total_per_day
FROM A
)
GROUP BY
b_id,
total_per_day,
total_response_per_day,
TRUNC( dt, 'HH' )
ORDER BY
TRUNC( dt, 'HH' )
Results:
| B_ID | HOUR | TOTAL_RESPONSE_PER_HOUR | TOTAL_PER_HOUR | TOTAL_RESPONSE_PER_DAY | TOTAL_PER_DAY | RATIO_FOR_RESPONSES | RATIO |
|------|---------------------|-------------------------|----------------|------------------------|---------------|---------------------|-------|
| 1 | 2018-09-18 00:00:00 | 2 | 3 | 6 | 8 | 0.3333333333333333 | 0.375 |
| 1 | 2018-09-18 01:00:00 | 2 | 2 | 6 | 8 | 0.3333333333333333 | 0.25 |
| 1 | 2018-09-18 02:00:00 | 0 | 1 | 6 | 8 | 0 | 0.125 |
| 1 | 2018-09-18 03:00:00 | 1 | 1 | 6 | 8 | 0.16666666666666666 | 0.125 |
| 1 | 2018-09-18 05:00:00 | 1 | 1 | 6 | 8 | 0.16666666666666666 | 0.125 |

Answer 3

SELECT withResponses.hour,
withResponses.cnt AS withResponse,
alls.cnt AS AllEntries,
(withResponses.cnt / alls.cnt) AS ratio
FROM
( SELECT to_char(d, 'DD-MM-YY - HH24') || ':00 to :59 ' hour,
count(*) AS cnt
FROM A
WHERE RESPONSE IS NOT NULL
GROUP BY to_char(d, 'DD-MM-YY - HH24') || ':00 to :59 ' ) withResponses,
( SELECT to_char(d, 'DD-MM-YY - HH24') || ':00 to :59 ' hour,
count(*) AS cnt
FROM A
GROUP BY to_char(d, 'DD-MM-YY - HH24') || ':00 to :59 ' ) alls
WHERE alls.hour = withResponses.hour ;
SQLFiddle: http://sqlfiddle.com/#!4/c09b9/2