Add modify bookings scripts and results

sql/cancel_booking.sql

@@ -0,0 +1,13 @@
+-- modify bookings - task 3
+-- add and update bookings - task 3
+-- noqa: disable=CP03,LT02,RF03
+create procedure CancelBooking (in BookingID int)
+begin
+    delete from Bookings as B
+    where B.BookingID = BookingID;
+    if row_count() = 1 then
+      select concat("Booking ", BookingID, " cancelled") as Confirmation;
+    else
+      select concat("Booking ", BookingID, " not cancelled - missing booking") as Confirmation;
+    end if;
+end