Overlapping Appointments

Return every pair of appointments (smaller id first) of the same doctor whose time ranges overlap. Appointments that only touch at an end point do not overlap. Order by the pair.

Table schema

Appointments(id INT PRIMARY KEY, doctor VARCHAR(5), start_time TIME, end_time TIME)

Sample data

id | doctor | start_time | end_time
1 | D1 | 09:00 | 10:00
2 | D1 | 09:30 | 10:30
3 | D1 | 11:00 | 12:00
4 | D2 | 09:00 | 10:00