41.  Explain the difference between an exclusive lock and a shared lock.

42.  Explain the difference between optimistic locking and pessimistic locking.

43.  What is deadlock? How can it be avoided? How can it be resolved once it occurs?

44.  What are the major functions of the database administrator?

45.  Explain what we mean by an ACID transaction.

46.  What are the ways in which an Oracle database can be created?

47.  What are sequences, and what are the possible problems when using them to create surrogate keys?

48.  Under what conditions should indexes be used?

49.  Explain the three levels of transaction isolation supported by Oracle.

50.  What are the types of files used in Oracle recovery?