Count Number of a Specific Day(s) Between Two Dates - mysql

Question

I have a single line in MySQL table: volunteers
user_id | start_date | end_date
11122 | 2017-04-20 | 2018-02-17
How can I find how many times the 3rd day or 24th day of a month appears? (i.e. 2017-05-03, 2017-06-03, 2017-12-24, 2018-01-24) I'm trying to get to the following count:
Sample Output:
user_id | number_of_third_day | number_of_twenty_fourth_day
11122 | 10 | 10
I look at the documentation online to see if there is a way I can say (pseudo):
SELECT
day, COUNT(*)
FROM volunteers
WHERE day(between(start_date, end_date)) in (3,24)
I tried to create a calendar table to no avail, but I would try to get the days, GROUP BY day, and COUNT(*) times that day appears in the range
WITH calendar AS (
SELECT start_date AS date
FROM volunteers
UNION ALL
SELECT DATE_ADD(start_date, INTERVAL 1 DAY) as date
FROM volunteers
WHERE DATE_ADD(start_date, INTERVAL 1 DAY) <= end_date
)
SELECT date FROM calendar;
Thanks for any help!

Answer 1

This one is more optimized since I generate date range by months not days as other questions, so its faster
WITH RECURSIVE cte AS
(
SELECT user_id, DATE_FORMAT(start_date, '%Y-%m-03') as third_day,
DATE_FORMAT(start_date, '%Y-%m-24') as twenty_fourth_day,
start_date, end_date
FROM table1
UNION ALL
SELECT user_id,
DATE_FORMAT(third_day + INTERVAL 1 MONTH, '%Y-%m-03') as third_day,
DATE_FORMAT(twenty_fourth_day + INTERVAL 1 MONTH, '%Y-%m-24') as twenty_fourth_day,
start_date, end_date
FROM cte
WHERE third_day + INTERVAL 1 MONTH <= end_date
)
SELECT user_id,
SUM(CASE WHEN third_day BETWEEN start_date AND end_date THEN 1 ELSE 0 END) AS number_of_third_day,
SUM(CASE WHEN twenty_fourth_day BETWEEN start_date AND end_date THEN 1 ELSE 0 END) AS number_of_twenty_fourth_day
FROM cte
GROUP BY user_id;
Demo here

Answer 2

A dynamic approach is.
but creating the dateranges, takes a lot of time, so you should have a date table to get the dates
CREATE TABLE table1
(`user_id` int, `start_date` varchar(10), `end_date` varchar(10))
;
INSERT INTO table1
(`user_id`, `start_date`, `end_date`)
VALUES
(11122, '2017-04-20', '2018-02-17')
,(11123, '2019-04-20', '2020-02-17')
;
Records: 2 Duplicates: 0 Warnings: 0
WITH RECURSIVE cte AS (
SELECT
user_id,
`start_date` as date_run ,
`end_date`
FROM table1
UNION ALL
SELECT
user_id,
DATE_ADD(cte.date_run, INTERVAL 1 DAY),
end_date
FROM cte
WHERE DATE_ADD(date_run, INTERVAL 1 DAY) <= end_date
)SELECT user_id,
SUM(DAYOFMONTH(date_run) = 3) as day_3th,
SUM(DAYOFMONTH(date_run) = 24) as day_24th
FROM cte
GROUP BY user_id
user_id
day_3th
day_24th
11122
10
10
11123
10
10
fiddle

Answer 3

In last MySQL version you can use recursion:
-- get list of all dates in interval
with recursive dates(d) as (
select '2017-04-20'
union all
select date_add(d, interval 1 day) from dates where d < '2018-02-17'
) select
-- calculate
sum(day(d) = 10) days_10,
sum(day(d) = 24) days_24
from dates
-- filter 10 & 24 days
where day(d) = 10 or day(d) = 24;
https://sqlize.online/sql/mysql80/c00eb7de69d011a85502fa538d64d22c/

Answer 4

As long as you are looking for days that occur in every month (so not the 29th or beyond), this is just straightforward math. The number of whole calendar months between two dates (exclusive) is:
timestampdiff(month,start_date,end_date) - (day(start_date) <= day(end_date))
Then add one if the start month includes the target day and one if the end month includes it:
timestampdiff(month,start_date,end_date) - (day(start_date) <= day(end_date))
+ (day(start_date) <= 3) + (day(end_date) >= 3)