Hi, I'm trying to complete an assignment regarding Oracle, and am finding my lecture notes too vague! I'm a student, so of course I have only 12 hours left to complete this or... Given that in each case the transactions are still in progress - can someone tell me: (a) At 1:03PM transaction A updates row R1 of table T. At 1:04PM transaction B updates row R1 of table T. What happens, and why? (I think that - B will be unable to update R1 because A�s transaction has placed a lock on R. Default level read committed will allow B to read committed transactions, but nothing else until A�s transaction completes). (b) Transactions A and B are both isolation level serializable. At 11:43AM transaction A updates row R2 of table T. At 11:44AM transaction B selects row R2 of table T. What happens, and why? (I think that - B will see R2, but be unable to do anything else until A commits) (c) Transactions A and B are both isolation level read committed. At 2:15PM transaction A updates row R3 of table T. At 2:15PM transaction B updates row R4 of table U. At 2:16PM transaction A updates row R4 of table U. At 2:17PM transaction B updates row R3 of table T. What happens, and why? (I know that - this is a deadlock, neither A nor B can move... I think that Oracle will kill off A's 2:16 transaction, but not sure whether the the 2:15 will be killed off, as the deadlock would still exist) Anybody in a sympathetic frame of mind who can help? Cheers, Nevin.