Question 1 :
Rollback causes work in the current transaction to be undone.
Question 2 :
Savepoint is a point within a particular transaction to which you may rollback without rolling back the entire transaction.
Question 3 :
Set Transaction is to establish properties for the current transaction.
Question 4 :
Locking are mechanisms intended to prevent destructive interaction between users accessing data. Locks are used to achieve.
Question 5 :
Consistency : Assures users that the data they are changing or viewing is not changed until the are thro' with it.