I have a table on booking orders for trips.

Bookings (order_no, user_id, booking_time,cancel_time,complete_time)

I try to write a query to return the order_no from all rows where customers made concurrent bookings (i.e. where a customer made a new booking before they completed or cancelled the previous booking).

Customer A booked an order #000 at 1:00, and completed it at 1:25.

Customer A booked an order #001 at 1:19, and completed it at 1:30.

Customer A booked an order #002 at 3:30, and completed it at 4:00.

Customer B booked an order #020 at 1:10, and completed it at 2:00.

Customer B booked an order #021 at 4:00, and completed it at 4:05.

Only Customer A had a concurrent booking. The query would return order_no #000 and #001.

Sample Output

#000

#001

SELECT a.user_id

FROM Bookings a JOIN Bookings b ON a.user_id = b.user_id AND a.order_no <> b.order_no

WHERE

    (b.booking_time  < a.complete_time OR b.booking_time < a.cancel_time) AND

    (b.complete_time > a.booking_time OR b.cancel_time> a.booking_time

the issue is some record have complete_time but cancel_time is null, while the others have cancel_time but complete_time is null

I need help with this, Please someone help me