Re: Informix vs. Sybase vs. Oracle vs. (gasp) MS SQL Server

Pablo Sanchez wrote: > I phoned two airline companies: United and US Air. I Wow! Someone's bothering to do some leg work rather than just making blind assumptions. > interviewed the person taking reservations and here are the > responses: > > US Air: > ------- > You can view the list of available seats and present that to > the customer. If the customer requests that seat, they go > through the reservation process and that seat *may* be > swiped by another office. That is, there's no lock that is > placed on that seat. I can't see much point in locking all the seats in the expectation that one may be reserved. I don't expect the display to show reservations being taken in real time or can it? (Messaging between a backend and a registered app?) > I interpreted this in db terms as follows: > > tx #1: > > select list of available seats for flight number Isn't the display graphical and shows all seats and their current status? > tx #2: > > begin tx > update seat_table where flight_number is the one we are on > and it's not already taken > if taken, failure ... rollback tran > else, print "happy days are here" > > I believe that this is SABRE. Careful, thats an assumption. > United Airlines > --------------- > You can lock a seat if you have a specific seat in mind > without making a reservation yet. You can make the > reservation and have that seat. If the system crashes > between locking the seat and making the reservation, the > seat remains locked. (I found this interesting). What if its already locked? > I interpret this in db terms as follows: > > tx #1: > > select list of seats.... > > tx #2: > > update seat_table .... (as before) > > tx #3: > > update reservation_table What bugs me is that you STILL get overbooking! Is there anyone that can explain that? (Not that I'm complaining mind you. They usually promote you up.) -am