datetime - MySQL: Is it possible to create a query that evaluates data from different records?

Question

I've got a table like this. It shows the starttime and endtime of different restaurants on different weekdays.

No	Restaurant	Weekday	Starttime	Endtime
1	A	Mon	10:00	21:00
2	A	Tue	10:00	21:00
3	A	Wed	19:00	08:00
4	A	Thu
5	A	Fri	10:00	21:00
6	A	Sat	10:00	21:00
7	A	Sun	19:00	08:00
8	B	Mon	11:00	21:00
9	B	Tue	11:00	21:00
10	B	Wed	11:00	23:00
11	B	Thu	11:00	23:00
12	B	Fri	11:00	16:00
13	B	Sat	10:00	00:00
14	B	Sun	00:00	13:00

Answer 1

You can split to 2 rows each row that contains Endtime of the next day:

WITH cte AS (
  SELECT *, Weekday day, Starttime time1, Endtime time2 FROM user_time
  WHERE Starttime < Endtime 
  UNION ALL
  SELECT *, Weekday, Starttime, '23:59' FROM user_time
  WHERE Starttime > Endtime 
  UNION ALL
  SELECT *, 
         DATE_FORMAT((STR_TO_DATE(CONCAT(LEFT(CURRENT_DATE, 8), Weekday), '%X-%V-%W') + INTERVAL 1 DAY), '%a'), 
         '00:00', Endtime 
  FROM user_time
  WHERE Starttime > Endtime
)  
SELECT No, Restaurant, Weekday, Starttime, Endtime 
FROM cte
WHERE day = DATE_FORMAT(CURRENT_DATE, '%a')
  AND NOW() BETWEEN CONCAT(CURRENT_DATE, ' ', time1, ':00') AND CONCAT(CURRENT_DATE, ' ', time2, ':00') 

See the demo.