Alan Acosta wrote: > But i have a new problem there, i have no rows for update, i create new rows > when the seats are sold, cause rarely the database knows the capacity of the > bus, number of seats, even some bus doesn't have seat number 4 for example > :p. So i cannot SELECT FOR UPDATE no existent rows, but i still need to lock > in some way in order to check if seat number X was already sold or is free ! Sounds like you need a uniqueness constraint of some sort to detect when the seat has been sold already when you try the insert. Bosco. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general