获取 MySQL 中 2 个日期之间的日期？

Question

How do you get list of dates inside of 2 dates?

Currently in my booking table I have 2 fields like starts_at and ends_at

If I use a query something like this

SELECT starts_at, ends_at FROM booking

This will give me all of records exists

But what I want is to list all of dates records uniquely

Let say in the first row of record 2020-08-19 to 2020-09-16

This will be the output

    2020-08-19
    2020-08-20
    2020-08-21
    ......continuation
    2020-09-15
    2020-09-16

and on the second row there is 2020-06-04 to 2020-06-09

This will be

 2020-06-04
 2020-06-05
 2020-06-06
 2020-06-07
 2020-06-08
 2020-06-09

as you can see all between dates are being dropdown.

and the final output of that should be the collected dates will be arranged based on the recent like this

 2020-06-04 (added dates from 2nd row)  
 2020-06-05
 2020-06-06
 2020-06-07
 2020-06-08
 2020-06-09

 2020-08-19 (added dates from 1st row)
 2020-08-20
 2020-08-21
 ......continuation
 2020-09-15
 2020-09-16

Just in case some dates are being duplicated it should be counted/read as one. since all days are being arranged.

Answer 1

For MySQL 8+

WITH RECURSIVE
cte AS ( SELECT starts_at, ends_at, starts_at single_date 
         FROM booking
         UNION ALL
         SELECT starts_at, ends_at, single_date + INTERVAL 1 DAY
         FROM cte
         WHERE single_date < ends_at )
SELECT DISTINCT single_date
FROM cte
ORDER BY 1;

For MySQL 5+ you must use generated numbers table with the numbers from 0 to at least MAX(ends_at - starts_at) :

SELECT DISTINCT booking.starts_at + INTERVAL n.n DAY single_date
FROM booking
-- assuming 99 days is enough
JOIN ( SELECT n1.n*10+n2.n n
       FROM (SELECT 0 n UNION SELECT 1 UNION ... UNION SELECT 9) n1
       JOIN (SELECT 0 n UNION SELECT 1 UNION ... UNION SELECT 9) n2 ) n
WHERE booking.starts_at + INTERVAL n.n DAY <= booking.ends_at;